SURGICAL ANATOMY OF THE HAND AND UPPER EXTREMITY part 05

 

CHAPTER

JAMES R. DOYLE

1 0

HAND

PART

PALMAR HAND

The complex and compact nature of the hand, the terminal

organ of the upper extremity, illustrates the need for a clear

understanding of the anatomy of this organ. Although the

hand cannot be functionally separated from the upper

extremity, it is the hand that obtains information from the

environment, which it passes to the brain and ultimately executes a given function in conjunction with the remaining

components of the upper extremity. Positioning this functional unit in space is made possible from a mechanical viewpoint by three joints that provide a series of mobile yet constrained linkages that allow an extraordinary selection of

positions to achieve multiple functional demands. The most

mobile, the shoulder, is joined by the progressively less mobile

wrist and elbow joints. The unique design of the elbow and

two-bone forearm allows a significant arc of flexion and

extension as well as pronation and supination of the forearm.

The hand is under central control, mediated by specialized

end organs and nerve endings in and beneath the skin, as well

as by joint receptors. Although the hand also may be under

visual control, this modality is a less effective control method

compared with the modalities of sensibility and proprioception. Witness the effective use of the hand by a blind person

compared with the relatively poor hand function in a sighted

person with loss of sensibility due to Hansen’s disease.

DESCRIPTIVE ANATOMY OF THE PALMAR

HAND

Contents

Bone: The metacarpals and phalanges of the five rays.

Blood Vessels: The terminal branches of the radial and

ulnar arteries.

Nerves: The terminal branches of the median and ulnar

nerves.

1

Tendons: The extrinsic flexor tendons of the five rays.

Muscles and Fascia: The intrinsic muscles, the thenar

and hypothenar muscles, and the palmar fascia.

External Landmarks

Important superficial landmarks on the palmar surface of the

hand include the pisiform bone, the thenar and hypothenar

eminences, and the thenar, proximal palmar, distal palmar,

digital, and distal wrist flexion creases (Fig. 10.1).

Pisiform Bone

The pisiform bone, located on the ulnar and palmar aspect

of the base of the hand, provides a visible and palpable landmark, which aids in the identification and location of the

flexor carpi ulnaris (FCU) tendon, the underlying ulnar

neurovascular bundle, and the hook process of the hamate.

Thenar and Hypothenar Eminences

The thenar eminence is formed by the abductor pollicis

brevis (APB) and flexor pollicis brevis (FPB), which overlie

the opponens pollicis (OP). The less prominent hypothenar

eminence on the ulnar side of the hand is formed by the

corresponding muscles of the small finger.

Flexion Creases

The wrist, thenar, palmar, and digital flexion creases are skin

flexion lines seen in the vicinity of synovial joints, where the

skin is attached to the underlying fascia (1). McGrouther has

shown that the fascial attachments in the palmar creases are

greatest adjacent to the creases rather than directly under the

crease (2). These creases have been recognized as useful

anatomic landmarks because of their relationship to underlying structures (3). Digital creases facilitate movement of the

digits without impingement by providing “folding points” in

the skin similar to the creases in a folded road map, and

because of strong attachments to the underlying fascia, they

also provide the stability to the skin required for forceful

grasping. These creases may begin as flexional skin folding of

the hand during fetal development (4). Dual creases are present at the proximal interphalangeal (PIP) joints, no doubt to

accommodate for the comparatively increased demands of

flexion at these joints compared with the metacarpophalangeal (MCP) and distal interphalangeal (DIP) joints. The

proximal crease at the PIP joint is the most prominent and is

the crease used in measurements to determine the location of

the underlying joint. The approximate orientation of the

creases is at right angles to the longitudinal axis of the corresponding digit and parallel to the flexion–extension joint axis.

Thus, the pronounced obliquity of the thenar crease is readily

apparent, as is the lesser obliquity of the proximal and distal

palmar creases. What is not so readily apparent, however, is

the fact that only 1 of the 17 creases (the thumb MCP joint)

is directly over the corresponding joint. This relationship, in

which most of the flexion creases do not correspond to their

respective joints, is confirmed by looking at one’s own hand

and noting the fact that the proximal digital creases (sometimes called the MCP flexion creases) are between the MCP

and the PIP joints (5).

Digital Skin Creases

The distal digital skin creases are located consistently proximal to their corresponding DIP joints, lying at mean distances of 7 to 7.8 mm proximal to the joint. Middle digital

flexion creases also are located consistently proximal to their

corresponding PIP joints, with mean distances ranging

from 1.6 to 2.6 mm. Proximal digital skin creases are consistently located distal to their corresponding MCP joints,

with mean values ranging from 14.4 to 19.6 mm distal to

the joint. In the thumb, the interphalangeal joint flexion

crease is located proximal to the interphalangeal joint by a

mean distance of 2.2 mm, whereas the MCP flexion crease

is found to pass obliquely and directly over the MCP joint

(5).

Palmar Skin Creases

The palmar skin creases, along with the proximal digital

creases, are related to the MCP joints. Although these

creases demonstrate a variable course in the palm, the distal

palmar crease, originating on the ulnar side of the palm, is

on average 7.9 mm proximal to the small finger MCP joint,

10.3 mm proximal to the ring finger MCP joint, and 6.9

mm proximal to the long finger MCP joint. The proximal

palmar crease, originating on the radial side of the hand, is

on average 9.1 mm proximal to the index finger MCP joint,

18 mm proximal to the long finger MCP joint, and 22.1

mm proximal to the ring finger MCP joint. A straight line

drawn joining the lateral border of the proximal palmar

10.1 Palmar Hand 533

FIGURE 10.1. A, B: Landmarks of the palmar hand.

A

B

crease and the medial aspect of the distal palmar crease

accurately identifies the location of the metacarpal necks in

most hands. (5)

Thenar Crease

The thenar crease usually intersects the lateral side of the

proximal palmar crease and curves obliquely across the

palm to intersect the distal wrist crease near the wrist center. In the mid-portion of the palm, the thenar crease is

located directly over the long finger metacarpal over half the

time. In the proximal palm, the thenar crease crosses the

capitate nearly half the time and the trapezoid approximately one-third of the time. Mean distance from the

thenar crease to the center of the trapeziometacarpal joint is

22.6 mm. The thenar crease passes 18.7 mm from the

hamate hook on the medial side of the carpus (5).

Distal Wrist Crease

Although there usually are three wrist flexion creases, only the

distal crease is of sufficient consistency to be used as a reliable

landmark. The distal wrist crease is located over the proximal

carpal row and passes over the scaphoid waist in almost all

instances and over the pisiform 80% of the time. The lunate

is consistently proximal to the distal wrist crease, with its center being an average of 9.2 mm from the crease. The radiocarpal joint is 13.5 mm proximal to the distal wrist crease, and

the center point of the distal radioulnar joint is 21.1 mm

proximal to the wrist crease. On the lateral side of the wrist,

the distal wrist crease is within 1 mm of the center of the

scaphoid waist. The mid-portion of the trapeziometacarpal

joint averages 19.4 mm distal to the distal wrist crease. On the

ulnar side of the wrist, the pisiform is directly under or slightly

distal to the crease. The base of the ulnar styloid is on average

11.7 mm proximal to the distal wrist crease (Fig. 10.2).

534 Regional Anatomy

FIGURE 10.2. Digital, palmar, thenar,

and wrist flexion creases and their relationship to the underlying joints and

bones.

Relationship of Deeper Structures to

Superficial Landmarks

Kaplan described a unique system of lines drawn on the palmar side of the hand that coincided with important deeper

structures (6). These lines may facilitate the recall and identification of important deeper structures in the hand. These

lines and corresponding underlying structures are depicted

in Figure 10.3.

Skeletal Anatomy

The Five Rays of the Hand

Thumb

The thumb is a continuation of the lateral column of the

carpus formed by the scaphoid and trapezium. The trapezium and scaphoid longitudinal axis is at a 45-degree angle

to the index metacarpal and the carpus, which accounts for

the functional separation between the first and second rays.

This position and the sellar configuration of the trapeziometacarpal joint allows the thumb to oppose the tips of the

digits for pinch.

Thumb Metacarpal. The thumb metacarpal is short and

thick. Its dorsal or extensor surface is transversely convex

and the palmar or medial surface is longitudinally concave.

Fingers

Each of the four fingers is of different length. In flexion, the

centrally positioned long finger flexes in a line parallel with

the long axis of the hand, whereas the index, ring, and small

fingers converge toward the central digit. This may be confirmed by comparing finger motion in one’s own hand and

by noting the transverse orientation of the proximal digital

flexion crease of the long finger compared with the progressively oblique orientation of the index, ring, and small

fingers. Each of the MCP flexion creases are at approximate

right angles to the longitudinal arc of motion and thus confirm the fact that the longitudinal arcs of motion of the

index, ring, and small fingers are convergent (see Fig. 10.2).

10.1 Palmar Hand 535

FIGURE 10.3. Relationship of deeper structures to skin reference lines. Kaplan described a

unique system of lines drawn on the palmar side of the hand that coincided with important

deeper structures (6). These lines may facilitate the recall and identification of important deeper

structures in the hand.

The obliquity of the proximal and distal palmar creases

(which converge in flexion) roughly parallels the oblique

transverse palmar axis, which forms an angle of 75 degrees

with the longitudinal axis of the long finger ray.

Index Metacarpal. The index metacarpal is the longest of

the metacarpals and has the largest base. The shaft is triangular and longitudinally concave toward the palm. The distal dorsal surface is broad but proximally narrows to a

ridge.

Long Finger Metacarpal. The shaft of this metacarpal

resembles the index metacarpal. A short proximal styloid

process is present dorsally and laterally. The extensor carpi

radialis brevis (ECRB) attaches distal to this styloid process.

Ring Finger Metacarpal. The ring finger metacarpal is

shorter and thinner than the index and long fingers, but the

shaft is similar in configuration to the index finger.

Small Finger Metacarpal. The small finger metacarpal

differs on its medial surface, which is nonarticular and has

a tubercle for attachment of the extensor carpi ulnaris

(ECU). The shaft has a triangular dorsal area that almost

reaches the base.

Longitudinal and Transverse Arches

The normal hand is “cupped” in both its long and transverse axes. The static aspects of this transverse cupping are

accounted for by the prominence of the thenar and

hypothenar eminences as well as by the transverse osseous

arches at the distal carpal row and at the neck of the

metacarpals. Further dynamic cupping is achieved by convergent movement of the thumb and small finger. The static aspects of the longitudinal cupping are due to the proximal prominence of the thenar and hypothenar eminences

and the natural palmar concavity of the metacarpals and

phalanges. The dynamic aspects of the longitudinal cupping relate to the powerful intrinsic and extrinsic flexors,

which maintain an attitude of flexion in the fingers (Fig.

10.4).

Comparative Mobility of the Metacarpals

The thumb metacarpal is the most mobile of the five

metacarpals, followed by the ring and small finger, with the

small finger ray being the most mobile of the fingers. The

comparative increased mobility of the thumb is explained

by the sellar nature of its carpometacarpal (CMC) joint,

which is discussed later. Compared with the more mobile

ring and small finger metacarpals, the index and middle finger metacarpals are relatively fixed. The comparative mobility of the ring and small finger metacarpals aids in cupping

the hand and in the mechanics of pinch between the ring

and small fingers and the thumb. This is readily demonstrated on one’s own hand by noting the passive mobility of

the small and ring finger metacarpals compared with the

more rigid middle and index fingers, and the active mobility and palmar flexion of the small and ring finger

metacarpals when making a fist.

Phalanges of the Hand

There are 14 phalanges, 3 in each finger and 2 in the

thumb. Each has a head, shaft, and base. The shaft tapers

distally and its dorsal surface is transversely convex (1). The

palmar surface is longitudinally concave. The bases of the

proximal phalanges are concave and transversely oval to

accommodate the metacarpal head. The bases of the middle

phalanges have two concave facets arranged side by side and

separated by a vertical ridge to accommodate the dual articular condyles of the proximal phalanx. A similar but less

pronounced arrangement is present between the middle

and distal phalanges.

Carpometacarpal Joints

Thumb Carpometacarpal

Joint Type. The CMC joint of the thumb is classified as

a sellar joint, which means that its articular surfaces are

convex in one plane and concave in the second plane,

which is at approximately right angles to the first plane

(Fig. 10.5). The convexity of the larger surface is apposed

to the concavity of the smaller surface, and vice versa.

536 Regional Anatomy

FIGURE 10.4. Longitudinal and transverse arches of the hand.

The normal hand is “cupped” in both its long and transverse

axes.

Although primary movements may occur in two orthogonal planes (flexion–extension and abduction–adduction), the articular shape also allows axial rotation (pronation, supination), which is especially important in the

movement of opposition needed for pulp-to-pulp pinch

between the thumb and adjacent digits. A joint is said to

be in the position of “close pack” when its articular surfaces are in maximum congruence, maximum contact,

tightly compressed, or “screwed home,” and with the

joint capsule and ligaments maximally taut (1). Sellar surfaces are fully congruent in only one position, and in the

thumb CMC joint this position corresponds with full

opposition.

Joint Axes. The CMC joint of the thumb has two axes of

rotation, one in the trapezium (the flexion–extension axis)

and one in the thumb metacarpal (the abduction–adduction axis) (7). Two axis joints can be visualized as two hinges

welded together. If the two hinges are perpendicular to the

anatomic planes, only flexion–extension and abduction–

adduction can occur. However, if the axes of rotation are

offset (not perpendicular to the bones or to each other)

from the anatomic planes, flexion–extension may occur

with some varus/valgus and internal/external rotation. Similarly, the second primary axis of abduction–adduction may

be associated with flexion–extension and internal/external

rotation. It is the offset of the hinges or axes that allows the

thumb to pronate with flexion and thus to perform pulpto-pulp pinch with the small finger or properly grasp

objects such as a hammer. The thumb also needs to be in

neutral rotation when extended for wide grasp. If an independent axis were used to achieve this pronation, at least

two more motors would be needed, and the base of the

thumb and the palm would be so full of thumb muscles

that grasp would be extremely awkward (7). A tendon that

crosses a two-axis joint has an effect on every hinge or axis

it crosses. Fortunately, in the normal situation, the resultant

forces are balanced, which results in stability and power

(Fig. 10.6).

10.1 Palmar Hand 537

FIGURE 10.5. Carpometacarpal joint of the thumb.

FIGURE 10.6. Joint axes of the CMC joint of the thumb.

Stabilizing Ligaments of the Carpometacarpal Joint of

the Thumb. In the CMC joint of the thumb, ligaments

provide joint stability during pinch and grasp (8). Loss of

ligamentous support is believed to be a primary cause of

degenerative arthritis (8–10). Based on a study of 30 hands,

Imaeda et al. identified five main ligaments as supporting

structures of the thumb CMC joint. Three were found to

be intracapsular, and two extracapsular (8). A more recent

study of 37 hands from the same laboratory divided 2 of the

initially described ligaments (anterior oblique and intermetacarpal) into 2 distinct ligaments, making a total of 7

stabilizing ligaments of the CMC joint of the thumb (11).

In both the Imaeda et al. and Bettinger et al. studies, the relative laxity or tautness of each ligament was tested in a variety of positions and the origin and insertion of each ligament were determined. In the Imaeda et al. study, the status

of each ligament was correlated with the Eaton stage of

arthritis noted in the joint (8,12). The more recent study by

Bettinger et al. is presented in Table 10.1 and includes their

nomenclature and the origin, insertion, width, thickness,

and prevalence of the stabilizing ligaments of the thumb

CMC joint. The following descriptive comments are based

on the studies of the thumb CMC joint ligaments by

Imaeda et al. and Bettinger et al. (8,11).

Superficial Anterior Oblique Ligament. The superficial anterior oblique ligament (SAOL) is a thick, broad structure

that is taut at the extremes of rotation, especially pronation,

and while the joint is extended (11). In addition, the SAOL

limits palmar subluxation in pronation, supination, or neutral. Except in maximal extension, this ligament appears lax

and redundant in all hands regardless of the amount of

articular thinning or frank eburnation of the joint. This

may reflect the laxity required to accommodate pronation

during thumb opposition (11).

Deep Anterior Oblique Ligament. The deep anterior oblique

ligament (DAOL), also known as the beak ligament, is deep

to the SAOL and can be easily separated from it when

approached from within the CMC joint. It is said to be an

intraarticular ligament that lies in the concavity of the trapezium, and is the closest ligament to the center of the joint. It

serves as a pivot point for rotation, specifically pronation; it

becomes taut in wide abduction or extension.

The DAOL prevents extreme ulnar subluxation during

abduction loading. Both the DAOL and SAOL stabilize the

thumb metacarpal against palmar subluxation. The DAOL is

taut in pronation and wide palmar and radial abduction (11).

Author’s comment: In the Imaeda et al. study, the SAOL

and DAOL were considered to be one ligament, the anterior

oblique ligament (AOL) (8). The AOL was consistently

observed in 24 normal joints of the 30 hands studied. In

seven specimens with degenerative changes, the AOL was

normal in one case of Eaton stage II, attenuated in three cases

(two cases of Eaton stage III and one case of Eaton stage IV),

and completely destroyed in two specimens in which adduction contracture was present (Eaton stage IV) (8).

Ulnar Collateral Ligament. The ulnar collateral ligament

(UCL) is an extracapsular ligament and is taut in extension,

abduction, and pronation. The UCL is slightly ulnar

(medial) to the SAOL, which it partially covers (11). In the

Imaeda et al. study, specimens with degenerative arthritis

demonstrated a consistently present ligament, but it usually

was elongated (8).

Palmar Intermetacarpal Ligament. The palmar component

of the intermetacarpal ligament (IML) is extracapsular and

is taut in abduction, opposition, and supination. It stabilizes the thumb metacarpal during radiopalmar translation

of its base (11).

Dorsal Intermetacarpal Ligament. The dorsal component of

the IML (DIML) is an extracapsular ligament, and like the

palmar component is transversely oriented between the base

of the thumb and index metacarpals. It becomes taut in

538 Regional Anatomy

TABLE 10.1. STABILIZING LIGAMENTS OF THE CARPOMETACARPAL JOINT OF THE THUMB

Ligament Prevalence Origin Insertion Width (mm) Thickness (mm)

SAOL 100% Palmar tubercle trapezium Palmar-ulnar metacarpal 8.59 ± 2.61 1.34 ± 0.25

DAOLa 70% Palmar tubercle trapezium Palmar-ulnar metacarpal 5.45 ± 0.45 1.17 ± 0.15

UCL 100% Transverse carpal ligament Palmar-ulnar metacarpal 3.35 ± 0.33 0.83 ± 0.12

DRL 100% Dorsoradial trapezium Dorsal base first metacarpal 11.39 ± 1.92 2.25 ± 0.33

POL 100% Dorsoulnar trapezium Dorsoulnar first metacarpal 4.97 ± 0.89 1.35 ± 0.28

IML 100% Dorsoradial 2nd metacarpal Palmar-ulnar first metacarpal 3.47 ± 1.26 1.03 ± 0.18

DIML 43% Dorsoradial 2nd metacarpal Dorsoulnar first metacarpal 3.70 ± 0.83 1.10 ± 0.08

SAOL, superficial anterior oblique ligament; DAOL, deep anterior oblique ligament; UCL, ulnar collateral ligament; DRL, dorsal radial ligament;

POL, posterior oblique ligament; IML, intermetacarpal ligament; DIML, dorsal intermetacarpal ligament.

aAttaches to articular margins of the trapezium and first metacarpal deep to SAOL.

After Bettinger PC, Linscheid RL, Berger RA, et al. An anatomic study of the stabilizing ligaments of the trapezium and trapeziometacarpal

joint. J Hand Surg [Am] 24:786–798, 1999.

pronation and with dorsal and radial translation of the base

of the thumb metacarpal, and appears primarily to restrain

pronation of the thumb metacarpal (11).

Author’s note: In the Imaeda et al. (8) study, the ligament

complex between the base of the thumb and index

metacarpal was considered to be one ligament, the IML. In

23 of 30 specimens, it was a moderately thin structure and

its appearance did not correlate with the degree of degenerative joint changes. In the other 7 specimens, the IML was

large and resembled the fan portion of the collateral ligament of the PIP joint. At the medial side of the CMC joint,

the IML and UCL form an L-shaped ligament that is an

important secondary stabilizer of the CMC joint.

Posterior Oblique Ligament. The posterior oblique ligament

(POL) is a capsular ligament and is partially covered by the

extensor pollicis longus (EPL) tendon. The POL is taut at

the extremes of abduction, opposition, and supination and

resists ulnar translation of the metacarpal base during

abduction and opposition (11). No attenuation of the ligament was seen in arthritic specimens (8).

Dorsoradial Ligament. This capsular ligament is the widest

and thickest of the stabilizing ligaments of the CMC joint

of the thumb. It is fan shaped and its origin on the trapezium is narrower that its insertion on the metacarpal. The

dorsoradial ligament (DRL) is taut with a dorsal or dorsoradial subluxating force in all positions of the CMC joint

except full extension. In addition, the DRL tightens in

supination regardless of joint position and tightens in

pronation when the CMC joint is concomitantly flexed.

According to Imaeda et al., it appears to serve mainly as a

check-rein to lateral CMC subluxation or dislocation (8).

Laxity of this ligament was observed only in Eaton stage IV

osteoarthritis (8) (Fig. 10.7).

Clinical Significance. Imaeda et al. concluded that although

there is no single ligament that provides sole joint stability

in a normal thumb CMC joint, the AOL appears to be the

most important ligament and is commonly attenuated in

cases of arthritis (8). The IML (Imaeda et al. classification),

the POL, and the UCL are secondary stabilizers that

become attenuated after failure of the primary stabilizer, the

10.1 Palmar Hand 539

FIGURE 10.7. A–C: Carpometacarpal thumb joint ligaments. Dorsal view (B), Palmar view (C).

SAOL, superficial anterior oblique ligament; DAOL, deep anterior oblique ligament; AOL, anterior oblique ligament; UCL, ulnar collateral ligament; IML, intermetacarpal ligament; DIML, dorsal intermetacarpal ligament; POL, posterior oblique ligament; DRL, dorsoradial ligament.

(Redrawn after Imaeda T, Kai-Nan A, Cooney WP III, et al. Anatomy of trapeziometacarpal ligaments. J Hand Surg [Am] 18:226–231, 1993, and Bettinger PC, Linscheid RL, Berger RA, et al. An

anatomic study of the stabilizing ligaments of the trapezium and trapeziometacarpal joint. J

Hand Surg [Am] 24:786–798, 1999, with permission.)

A B C

AOL. The DRL acts as a check-rein for gross radiodorsal

subluxation or dislocation, but probably does not play a

major role in the initial stages of CMC joint instability. In

a normal joint, the direction of the resultant force in tip

pinch is directed radiodorsally and proximally (13). Compression forces may reach 13 times the applied load. In

addition, shear forces may reach 2.5 to 3 times the applied

load and torsional loading of 4 to 6 kg/cm can produce

instability of the CMC joint of the thumb, which can be

resisted only by strong support from ligaments on the

medial side of the CMC joint of the thumb (8). Pellegrini

noted a strong association between advanced degenerative

arthritis and deterioration of what he calls the beak ligament

(10). This so-called beak ligament, the AOL (Imaeda et al.

classification) (8), and the DAOL (Bettinger et al. classification) (11) in all probability are the same structure.

Author’s note: Anatomic studies have identified five to

seven stabilizing ligaments about the CMC joint of the

thumb. Relative importance has been given to these ligaments based on (a) observing the tautness of the ligaments

in various positions of the thumb metacarpal; (b) measuring the length, width, thickness, and prevalence of the various ligaments; and (c) correlating the status of the ligaments in relationship to the presence and degree of arthritic

changes in the CMC joint (8,11). Future studies may

include serial sectioning of various ligaments to note the

effect on stability (11). In addition, a currently used and

established technique for restoration of ligamentous stability at the thumb CMC joint reconstructs the palmar ligamentous complex as well as some element of the dorsal ligament by means of a tendon graft (14). If the concept is

correct that ligament morphology (cross-sectional area),

fiber direction, and location reflect to some degree functional demand secondary to direction and amount of force,

then relative importance may be attached to each of the ligaments. The fact that the Eaton and Littler reconstruction

is successful in restoring thumb CMC joint stability may

reflect this concept and allow the conclusion that both palmar and dorsal ligaments are necessary to stabilize this complex joint. Based on this concept, the palmar ligamentous

complex (AOL) and the DRL may be the primary stabilizers of the thumb CMC joint. Further information about

the relative stabilizing effect of all of the ligaments about

the CMC joint may come from evaluation of the ligament

status in acute as well as chronic subluxation or dislocation

of this joint.

Small to Index Finger Carpometacarpal Joints

Small. Examination of the CMC joints of the fingers

reveals that the small and ring finger CMC joints are

hinge joints, with the hamate presenting two concavities

for the convex bases of the small and ring fingers (1). The

lateral basal surface of the small finger metacarpal is transversely concave and convex from palmar to dorsal, and

articulates with a shallow concavity in the hamate. The

medial side is nonarticular and has a tubercle for attachment of the ECU.

Ring. The quadrangular articular surface of the ring finger

metacarpal, which articulates with the hamate, is convex

palmarly and concave dorsally.

Middle. The capitate has a comparatively plane base for

the middle finger metacarpal. The middle finger metacarpal

has a short styloid process that projects proximally from the

dorsal and lateral surface and is proximal to the attachment

of the ECRB.

Index. The index metacarpal is mortised between the capitate and trapezium, and further stability is added by an

anteroposteriorly directed ridge on the trapezoid that fits

like a wedge into the base of the index metacarpal. The

index metacarpal is the longest and has the largest base.

Comparative Finger Carpometacarpal Joint Stability/

Mobility. The comparative stability of the index and especially middle finger metacarpal with the more mobile ring

and small finger metacarpals may be understood by noting

the CMC joint configurations of the fingers as just

described. The middle finger metacarpal is like a fixed keel

or spine that supports the movement of the more mobile

adjacent digits and thumb.

Ligaments. Dorsal. Prominent dorsal ligaments connect the

dorsal surfaces of the carpal and metacarpal bones. The index

metacarpal has two, one each from the trapezium and trapezoid. The middle finger also has two, one from the trapezoid

and one from the capitate. The ring finger has two ligaments,

one from the capitate and one from the hamate. The small

finger metacarpal has a single band from the hamate that is

continuous with a single palmar ligament (1).

Palmar. The palmar ligaments are similar except that the

middle metacarpal has three ligaments, a lateral from the

trapezium, an intermediate from the capitate, and a medial

from the hamate.

Interosseous. Interosseous ligaments are present between the

distal aspect of the capitate and hamate and the adjacent

surfaces of the ring and small finger metacarpals.

Intermetacarpal Joints

The second to fifth metacarpal bases articulate with each

other by small, cartilage-covered facets. These articulations

are connected by dorsal, palmar, and interosseous ligaments.

Thumb Metacarpophalangeal Joint

Joint Type. The MCP joint of the thumb is classified as an

ellipsoid joint, which is characterized by an oval convex sur540 Regional Anatomy

face proximally that is opposed to an elliptical concavity

distally (1).

Joint Motion. The primary arc of motion is flexion and

extension, although limited abduction–adduction and pronation–supination is present. The metacarpal heads of the

thumb and the fingers are not uniformly convex but are

adapted to shallow concavities on the base of the adjacent

phalanges. The convex metacarpal head is partially divided

on the palmar surface and thus almost bicondylar (1). The

distal articular surface of the thumb metacarpal, when

viewed from the dorsopalmar aspect, is only slightly curved,

in contrast to the finger metacarpals, which demonstrate a

significant curvature. This shape coincides with the limited

abduction–adduction seen in the MCP joint of the thumb.

Shape of the Articular Head of the Thumb Metacarpal.

The shape of the distal articular aspect of the thumb

metacarpal is different from the finger metacarpals in that

its dorsal side is slightly wider than the palmar side, and also

in that the articular surface is divided into two zones: one

that articulates with the proximal phalanx and another,

more palmar, that articulates with the sesamoids in the palmar plate (6) (Fig. 10.8). The radial condyle of the

metacarpal head has greater dorsopalmar height than the

ulnar, which allows some pronation of the proximal and

distal phalanges during flexion. Range of flexion varies from

thumb to thumb and is due to the variation in curvature of

the metacarpal head; more spherical heads are associated

with greater motion (15). There also is an increased incidence of soft tissue injury in joints with poor range of flexion (16).

Thumb Metacarpophalangeal Joint Stability. The MCP

joint of the thumb is stabilized by its capsule, ligaments,

and surrounding musculotendinous structures, and has little intrinsic stability from its shape (15).

Joint Axes. Many joints such as the wrist, CMC, and MCP

joints have two axes of rotation that allow greater freedom

of movement (7). The flexion–extension axis is in the

metacarpal passing under the epicondyles, and the abduction–adduction axis passes between the sesamoids just proximal to the beak of the proximal phalanx (7).

Ligaments. Palmar Plate. The palmar plate of the thumb

MCP joint is a thick, fibrocartilaginous structure that is

firmly attached to the base of the proximal phalanx and

forms the bottom of a two-sided box. The sides of the box

are made up of the collateral ligaments. The palmar plate

contains a radial and an ulnar sesamoid that articulate with

the palmar surface of the thumb metacarpal. These

sesamoid bones are buried in the substance of the palmar

plate, and their exposed dorsal articular surfaces are flush

with the inner surface of the palmar plate, covered with

hyaline cartilage, and articulate with the palmar facets on

the adjacent metacarpal head. The ulnar sesamoid is the

largest and its exposed palmar surface, which partially projects from the palmar plate, provides an insertion point for

a portion of the adductor pollicis. The smaller radial

sesamoid, which is similarly arranged in the palmar plate,

provides an insertion point for the tendon of the superficial

head of the FPB. In contrast to the largest sesamoid in the

body, the patella, which is imbedded in tendon (quadriceps

femoris), the hand sesamoid bones are imbedded in palmar

plates, and in the thumb provide attachments for tendons.

The palmar plate sesamoids in the thumb appear to provide

a stronger point of tendon attachment than the fibrocartilaginous palmar plate. The sesamoids also may react more

favorably than the fibrocartilaginous palmar plate to compression or other forces during joint movement.

Collateral Ligaments. The collateral ligaments of the MCP

joint of the thumb and fingers as well as the PIP and DIP

joints are divided into proper and accessory collateral ligaments (17). The proper collateral ligaments are composed

of strong, substantial cords that flank the joints, arise from

the posterior tubercle and adjacent pit on the side of the

metacarpal head, and insert on the palmar aspect of the

10.1 Palmar Hand 541

FIGURE 10.8. Shape of the articular head of the thumb

metacarpal. The shape of the distal articular aspect of the thumb

metacarpal (A) is different from the finger metacarpals (B) in

that (a) its curvature in the anteroposterior plane is flatter; (b) its

dorsal side is slightly wider than the palmar side; (c) its articular

surface is divided into two zones, one that articulates with the

proximal phalanx and the other, more palmar, with the

sesamoids in the palmar plate; (d) the radial condyle of the

metacarpal head has greater dorsal-palmar height than the

ulnar condyle, which allows some pronation of the proximal and

distal phalanges during flexion.

A B

adjacent phalanx. The accessory collateral ligaments span

between the cordlike proper collateral ligaments and the

palmar plate. The proper collateral ligaments become taut

in flexion because of the camlike arrangement of the

metacarpal head, as seen in the sagittal plane in both the

thumb and fingers because the palmar surface of the

metacarpal is wider than the dorsal surface. In contrast, the

accessory collateral ligaments are slack in full flexion. The

mean locations of the origin and insertion of the proper

UCL have been determined and are given in Figure 10.9.

The clinical significance of these findings are discussed in

the Clinical Correlations section.

Finger Metacarpophalangeal Joint

Joint Type. The finger MCP joints are structurally similar

to the thumb MCP joint. However, there is increased range

of abduction–adduction in the fingers compared with the

MCP joint of the thumb. The finger MCP joints are ellipsoid joints characterized by an oval convex surface that is

apposed to an elliptical but shallow concavity. The

metacarpal condyle, which has a larger anteroposterior axis

(resulting in a so-called cam effect), articulates with the base

of the proximal phalanx, which is smaller and concave and

has a larger transverse axis. This configuration permits a significant arc of flexion–extension as well as abduction–

adduction.

Joint Axes. Primary motion is about two orthogonal axes

(e.g., flexion–extension and abduction–adduction), which

may be combined as circumduction. When the MCP joints

are flexed, neither abduction nor adduction is possible

because the articular surface of the metacarpal is relatively

flat on the palmar surface and the collateral ligaments are

tight in flexion because of their eccentric attachments to the

heads of the metacarpals and the resultant camlike effect of

this arrangement (18). In addition, the palmar surface of

the finger metacarpal heads is wider than the dorsal side,

which also accounts for increased tension in the proper collateral ligaments when the joint is flexed. In contrast, the

accessory collateral ligaments are slack in full flexion.

Ligaments. Palmar Plate. The finger MCP palmar plates

are thick, dense fibrocartilaginous structures attached

firmly to the palmar base of the proximal phalanx and the

neck of the metacarpals. The attachment to the

metacarpals is by (a) the vertical fibers of the accessory

collateral ligaments, which span between the lateral and

medial margins of the palmar plate and attach to the palmar side of the proper collateral ligaments and the site of

origin of the proper collateral ligament; (b) the deep transverse IMLs, which are contiguous with the palmar plate

on each side; and (c) obliquely oriented fibers that arise

from the proximal corners of the palmar plate and attach

to the interosseous fascia. The arrangement of the vertically oriented accessory collateral ligaments may be compared with the vertical element of a pendulum, which

allows the counterweight or pendulum to swing to and fro

in a constrained arc. A somewhat similar arrangement is

present between the sagittal bands that course between the

extensor tendon and the sides of the palmar plate. Side or

lateral stability is provided by the attachments of the

transverse metacarpal ligaments, and proximal restraint by

the corner ligaments (Fig. 10.10). This arrangement,

along with the compressibility of the MCP palmar plate,

allows flexion of the MCP joint without impingement of

the palmar plate. The comparative morphology and internal structure of the palmar plates of the MCP and PIP

joints is of significance, and Watson and Dhillon have

stated that the MCP palmar plate, because of its fiber

arrangement, is compressible by as much as one-third of

its length, whereas the PIP palmar plate is more rigid (19).

This concept, as well as differences between the palmar

plates of the MCP and PIP joints, was studied by Gagnon

and associates, who noted (a) the mean MCP palmar plate

length was twice the length of the PIP joint palmar plate

(11.2 ± 1.62 mm vs. 5.6 ± 1.35 mm); (b) the mean thickness of the MCP palmar plate was 0.3 mm thinner than

the PIP palmar plate; and (c) the MCP palmar plate shortened 33.8% compared with 26.6% for the PIP palmar

plate during 90 degrees of flexion. Light and electron

microscopic examination of the MCP palmar plate

revealed loose connective tissue arranged in disorganized

strands, compared with the PIP joint palmar plate, which

consisted of more dense, homogeneous connective tissue.

Both palmar plates were relatively avascular and there was

no significant difference in cellularity either as to size or

numbers. Plate migration revealed that the MCP plate

migrated a mean of 7.85 mm or 79% of its length,

542 Regional Anatomy

FIGURE 10.9. The mean locations of the origin and insertion of

the proper ulnar collateral ligament. (Redrawn after Bean CHG,

Tencer AF, Trumble TE. The effect of thumb metacarpophalangeal ulnar collateral ligament attachment site on joint range

of motion: an in vitro study. J Hand Surg [Am] 24:283–287, 1999,

with permission.)

10.1 Palmar Hand 543

FIGURE 10.10. Finger metacarpophalangeal (MCP) joint complex. A: Note the

proper and accessory collateral ligaments, the palmar plate, and proximal

annular pulleys. B: Note the extensor tendon, sagittal band, and transverse

metacarpal ligament. C: Fresh cadaver dissection, right middle finger palmar

view, looking distally, showing the palmar plate, the transverse metacarpal ligament, and the proximal check-rein ligaments from the palmar plate. (continued on next page)

A

C

B

544 Regional Anatomy

FIGURE 10.10. (continued) D: Radial collateral ligament (RCL) complex, MCP joint of right

index finger, showing comparative laxity of the

RCL in extension. E: RCL of same digit in flexion

showing comparative tightness in the ligament.

F: Base of proximal phalanx of right index finger with metacarpal removed, showing boxlike

arrangement of palmar plate and collateral ligament complex (green marks). Note also the

articular depression in the RCL complex to

accommodate the radial condyle of the

metacarpal.

D

E

F

whereas the PIP plate migrated a mean distance of 6.39

mm or 139% of its initial length with 90 degrees of flexion. The fact that the PIP palmar plate is less compressible

probably accounts for its greater proximal migration (20).

The anatomic differences in the MCP and PIP palmar

plates, along with the presence of the more rigidly attached

check-rein ligaments at the PIP joint, may explain the

greater tendency of the PIP joint to develop palmar plate

contracture.

Transverse Metacarpal Ligaments. Three short, wide

fibrous bands connect the palmar plates of the index to

small finger metacarpals and prevent the metacarpals

from spreading. These ligaments often are referred to as

the deep transverse IMLs, perhaps to distinguish them

from the natatory ligaments, which are called the superficial transverse metacarpal ligaments. The convention

adopted in this text is transverse metacarpal ligaments and

natatory ligaments.

Collateral Ligaments. The collateral ligaments of the MCP

joint of the thumb and fingers as well as the PIP and DIP

joints are divided into proper and accessory collateral ligaments (17). The proper collateral ligaments are composed of strong, obliquely oriented cords that flank the

joints and that arise from the posterior tubercle and adjacent pit on the side of the metacarpal head and insert on

the palmar aspect of the adjacent phalanx. The accessory

collateral ligaments are more vertical and course between

the cordlike proper collateral ligaments and the palmar

plate.

Clinical Significance. In the finger MCP joints, the cordlike

components of the collateral ligaments become taut in flexion because of the camlike arrangement of the metacarpal

head in the sagittal plane and because the palmar surface of

the metacarpal is wider than the dorsal surface. This

explains why abduction–adduction movements are limited

in flexion and free in extension and why the MCP joints

should not be immobilized or allowed to remain in extension or hyperextension, which could result in irreversible

contracture (21). The asymmetry of the finger metacarpal

heads as well as the difference in length and direction of the

proper collateral ligaments explains the rotational movement of the proximal phalanx during flexion–extension and

why ulnar deviation of the digits is greater than radial deviation (21).

In the MCP joint of the index finger, the origin of the

radial collateral ligament (RCL) is more distal and closer to

the center of the joint space than the UCL. The radial ligament is longer—thus, more ulnar deviation is permitted

than radial deviation (21). The comparative range of radial

and ulnar deviation of the fingers at the MCP joint is given

in Table 10.2.

Proximal Interphalangeal Joint

Joint Type. The PIP joints are uniaxial hinge joints (1)

(Fig. 10.11). In contrast to the finger MCP joints, the PIP

joints are stable in all positions because of strong and sym10.1 Palmar Hand 545

TABLE 10.2. RADIAL AND ULNAR DEVIATION OF

THE FINGERS

Radial Deviation Ulnar Deviation

Digit (Degrees) (Degrees)

Index 13 43

Middle 8 34.5

Ring 14 20

Little 19 33

FIGURE 10.11. The proximal interphalangeal

(PIP) joint. The PIP joint is a uniaxial hinge joint

and, in contrast to the finger metacarpophalangeal joints, is stable in all positions because of

strong and symmetric proper collateral ligaments,

the palmar plate, and the osseous architecture in

the form of side-by-side concentric condyles that

articulate with matching glenoid concavities,

forming a dual shallow tongue-and-groove

arrangement.

metric proper collateral ligaments, the palmar plate, and

the osseous architecture in the form of side-by-side concentric condyles that articulate with matching glenoid

concavities, forming a dual shallow tongue-and-groove

arrangement.

Ligaments. Palmar Plate/Check-Rein Ligaments. The palmar plate of the PIP joint is a thick, short fibrocartilaginous

structure that is firmly attached both to the base of the middle phalanx and the neck of the proximal phalanx (Fig.

10.12). The attachments to the base of the middle phalanx

are most dense at the lateral margins, where the attachment

is confluent with the insertion of the collateral ligaments.

The palmar tubercle at the base of the middle phalanx,

which is prominent on a lateral radiograph, is devoid of significant insertion by the palmar plate. In its central 80%, the

palmar plate attaches by blending with the palmar periosteum of the middle phalanx. The attachments to the proximal phalanx (the check-rein ligaments) arise from bone and

begin just inside the distal edge of the second annular (A2)

pulley. The origins of the first cruciform (C1) pulley are on

the outside of the A2 pulley. The swallowtail configuration

of these proximal attachments of the palmar plate provides a

tension-relieving access route under the flexor sheath for the

branches of the digital vessels to reach the axial vincula.

Bowers et al. view the palmar plate as a static restraint limiting PIP joint extension (17). Sequential sectioning of the

various components of the complex suggested that the major

static resistance to hyperextension is offered by the confluent

distal lateral insertion of the palmar plate–collateral ligament

complex, where it cups the lateral flared margin of the phalangeal condyle. Based on biomechanical studies, Bowers et

al. suggested that the site and nature of injury to this complex depended on the rate of application of the deforming

force: Rapid rates produce rupture at the distal attachment

and slow rates attenuate the proximal check-rein ligaments.

Instability sufficient to permit dorsal dislocation occurred

only if there was interruption of the main collateral and

accessory collateral ligament complex in addition to disruption of the lateral attachments of the palmar plate from the

base of the middle phalanx (17).

Collateral Ligament. The collateral ligaments of the PIP

joints are divided into proper and accessory collateral ligaments (17) (Fig. 10.13). The proper collateral ligaments

are composed of strong cords that flank the joints and

arise from a concave fossa on the lateral aspect of each

condyle and then pass obliquely to insert on the palmar

side of the middle phalanx and distal-lateral margin of

the palmar plate. The accessory collateral ligaments span

between the cordlike proper collateral ligaments and the

palmar plate. The cordlike components of the collateral

ligaments demonstrate equal tension in flexion and

extension, in contrast to the proper collateral ligaments of

546 Regional Anatomy

FIGURE 10.12. Proximal interphalangeal

(PIP) joint palmar plate and check-rein ligaments. A: The palmar plate of the PIP

joint is a thick, short, fibrocartilaginous

structure that is firmly attached both to

the base of the middle phalanx and the

neck of the proximal phalanx. The attachments to the proximal phalanx (the checkrein ligaments) arise from bone and begin

just inside the distal edge of the second

annular (A2) pulley. The swallowtail configuration of these proximal attachments

of the palmar plate provides a tensionrelieving access route for the branches of

the digital vessels to reach the axial vinA cula by a route under the flexor sheath.

the finger MCP joints. The key to PIP joint stability is

the strong conjoined attachment of the collateral ligaments and the palmar plate. This ligament–box configuration results in three-dimensional strength that resists

PIP joint displacement. For displacement to occur, the

ligament–box arrangement must be disrupted in at least

two planes (22).

Clinical Significance. In contrast to the finger MCP joints,

which should be immobilized in flexion to avoid contracture of the proper collateral ligaments, the PIP joints are

immobilized in full extension to avoid irreversible contracture. The proper collateral ligaments at the PIP joints are

under relatively uniform tension in flexion and extension

and therefore are not a factor in irreversible contracture.

However, the check-rein ligaments at the proximal end of

the palmar plate at the PIP joint may hypertrophy and contract, resulting in a fixed flexion contracture.

Distal Interphalangeal Joint

The DIP joints are uniaxial hinge joints. The DIP joint is

structurally similar to the PIP joint, but demonstrates

10.1 Palmar Hand 547

FIGURE 10.12. (continued) B: Fresh cadaver

dissection of PIP joint, right middle finger,

“exploded” palmar radial view, proximal is to

the right. Note the distal aspect of the A2 pulley, remnants of the first cruciform (C1) pulley,

the check-rein ligaments, the palmar plate,

and the detached radial collateral ligament

complex (green marks). The extensor digitorum communis central slip (CS) attachment has

been incised and reflected distally. Note the

dorsal plate at the site of the CS attachment.

C: Same joint with proximal phalanx removed

and viewed from proximal-dorsal, showing

the boxlike configuration of the palmar plate

and collateral ligament complex (green

marks), central fenestration in the palmar

plate at the base of the middle phalanx, and

the check-rein ligaments (purple marks) and

the dorsal plate on the reflected CS. The key to

PIP joint stability is the strong conjoined

attachment of the collateral ligaments and the

palmar plate. This ligament–box configuration

results in three-dimensional strength that

resists PIP joint displacement. For displacement to occur, the ligament–box arrangement

must be disrupted in at least two planes.

B

C

548 Regional Anatomy

FIGURE 10.13. The proximal interphalangeal

(PIP) joint collateral ligament complex. A: The

accessory collateral ligaments span between the

cordlike proper collateral ligaments and the

palmar plate. B, C: Ulnar lateral view of the PIP

showing the cordlike components of the collateral ligaments that are under equal tension in

flexion and extension, in contrast to the proper

collateral ligaments of the finger metacarpophalangeal joints.

B

C

A

hyperextension during pulp contact, as in pinch, or during

forceful pressure on the distal aspect of the finger.

ANATOMIC RELATIONSHIPS

Arterial Supply of the Hand

The arterial supply to the hand is variable. The accuracy of

anatomic observations may be limited by many factors,

including observer bias, which may be expressed as the examiner’s willingness or unwillingness to perceive order amidst

diversity; quality of the specimen or injection technique; or

the lack of a sufficient number of specimens to verify a given

pattern or distribution (23). Large numbers of specimens in

a study may allow the observer to detect the influence of the

factors of parallel dominance/nondominance and range of

expression as seen especially in the arterial anatomy of the

hand. An example of parallel dominance/nondominance

relates to the palmar arches in the hand: As the dominance of

the superficial arch increases with an associated increase in

the size and number of its branches, the common and palmar

digital arteries, the dominance of the deep arch and its

branches, the palmar metacarpal arteries (PMAs), decreases.

And, of course, the reverse may be true, with the deep arch

and its branches becoming larger at the expense of the superficial arch and its branches. This dominance/nondominance

see-saw may be an explanation for the variations observed in

a particular study group or between groups. Vessels in the

hand may be seen to pass through a range of expression if sufficient numbers of hands are examined (24). Thus, a vessel

may be represented by a few tiny branches or it may reach its

maximum limit of distribution, and between these two

extremes a variety of intermediate stages may be seen (24).

Most of the arterial supply of the hand comes through

two main arteries, the radial and the ulnar. Other sources

include the median artery, which enters into formation of

the superficial palmar arch in approximately 10% of specimens, and the interosseous arteries, mainly the anterior,

which arise in the proximal forearm from the common

interosseous branch of the ulnar artery. The interosseous

arteries usually are unimportant under normal circumstances but may become significant if either the radial or

ulnar artery is injured. The typical or usual arrangement of

the arteries is presented in this section, along with anatomic

variations. The largest (650 cases) and relatively contemporary (1961) collection of dissections of the arterial patterns

in the hand is represented by the study of Coleman and

Anson, and much of the information that follows is based

on that study (25). The reader will soon appreciate that the

“textbook normal” configuration of the circulation in the

hand does not always represent the most common pattern.

The usual course, branching, and arch formation of the

radial and ulnar arteries in the hand are discussed, along

with common variations in these patterns. The arterial supply of the thumb and index finger is discussed last.

Radial Artery

The radial artery, near the radial styloid, lies to the radial side

of the flexor carpi radialis (FCR) and at approximately this

level gives off the palmar carpal branch, which usually joins a

companion vessel from the ulnar artery and the anterior

interosseous artery to form the palmar carpal arch (Fig.

10.14). At this level, the radial artery gives off the superficial

palmar branch, which passes through and occasionally over

the thenar muscles, which it supplies, and in approximately

one-third of individuals it joins the ulnar artery to aid in the

formation of the superficial palmar arch (1,25,26). The main

component of the radial artery passes dorsally beneath the

abductor pollicis longus and extensor pollicis brevis (EPB)

tendons to enter the anatomic snuff-box. After entering the

snuff-box, the radial artery gives off the dorsal carpal branch

to form part of the dorsal carpal arch. It then runs distally

beneath the EPL, passes between the bases of the thumb and

index metacarpals, through the first dorsal interosseous (DI)

muscle and into the palm, to end as a contributor to the deep

palmar arterial arch. The deep arch lies on the proximal ends

of the metacarpals and interossei, beneath the finger flexors

and the adductor pollicis (see Fig. 10.14).

Dorsal Carpal Arch

This dorsal plexus, which supplies the carpal bones, is

formed variously by radial, ulnar, or interosseous artery

branches (Fig. 10.15). Coleman and Anson identified 6

patterns in 75 specimens (25) (Fig. 10.16).

Type 1 (50%)

This pattern is formed by the dorsal carpal branch of the

radial artery, the carpal branches of the dorsal interosseous,

and the terminal branch of the palmar interosseous.

Type 2 (30%)

This pattern is formed by the dorsal carpal branches of the

radial and ulnar and interosseous arteries. The dorsal carpal

branch of the radial artery passes medially from the snuffbox under the EPL and radial wrist extensors to join the

dorsal carpal branch from the ulnar artery, which passes

over the head of the ulna and beneath the FCU and the

ECU to join its radial artery counterpart near the distal

carpal row. Dorsal branches from the anterior interosseous

and the dorsal interosseous complete the plexus.

Type 3 (8%)

This pattern is formed exclusively by the dorsal carpal

branch of the radial artery.

Type 4 (5%)

This pattern is formed by the dorsal carpal branches of the

radial and ulnar arteries.

10.1 Palmar Hand 549

Type 5 (3%)

This pattern is formed by the dorsal carpal branches of the

ulnar artery and the carpal branches of the palmar and dorsal interosseous arteries. The dorsal carpal branch of the

radial artery pierces the intermetacarpal musculature to join

the deep palmar arch.

Type 6 (4%)

No dorsal plexus is present.

Dorsal Metacarpal Arteries (Five in Number)

At the distal aspect of the dorsal carpal arch, three dorsal

metacarpal arteries (the second, third, and fourth) are

given off and course distally in the second, third, and

fourth intermetacarpal spaces (see Fig. 10.15). According

to Coleman and Anson, in their series of 75 specimens the

incidence of these arteries was second metacarpal artery,

99%; third metacarpal artery, 92%; and the fourth

metacarpal artery, 83%. The first dorsal metacarpal artery

arises from the main stem of the radial near its entry into

the first DI muscle. It usually is a small artery that bifurcates to send branches to the adjacent sides of the thumb

and index finger. Sometimes it is quite large and passes as

a single vessel over the dorsal surface of the first DI muscle to the distal margin of the adductor pollicis, where it

usually joins branches of the superficial palmar arch. Its

incidence in Coleman and Anson’s series was 18%. The

fifth dorsal metacarpal artery, which usually arises from

the dorsal carpal branch of the ulnar artery or occasionally

from the carpal branches of the interosseous arteries, was

found in 81% of Coleman and Anson’s series. It passes

distally along the outer margin of the small finger

metacarpal and usually extends as far as the PIP joint. At

approximately the same level of origin as the dorsal carpal

branch, the radial artery gives off the dorsal pollicis artery

to the dorsoradial aspect of the thumb. In Coleman and

Anson’s series, it was small but rather constant (83:100)

and rarely coursed further than the MCP joint of the

thumb. When the radial artery enters the palm between

the two heads of the first DI, it turns medially across the

base of the hand deep to the oblique head of the adductor

pollicis and then passes between its oblique and transverse

heads at the middle finger metacarpal or through its transverse head to the base of the small finger metacarpal

(1,25).

Deep Palmar Arch

At the base of the small finger metacarpal, the main stem of

the radial artery anastomoses with the deep branch of the

ulnar artery to form the deep palmar arch (Fig. 10.17). The

550 Regional Anatomy

FIGURE 10.14. Palmar view of right hand showing

radial and ulnar arteries, palmar carpal arch, and

superficial palmar arch.

10.1 Palmar Hand 551

FIGURE 10.15. Dorsal carpal arch, type I (the most common configuration), and the dorsal

metacarpal arteries, after Coleman and Anson (25). This dorsal carpal plexus that supplies the

carpal bones is formed variously by radial, ulnar, or interosseous artery branches.

deep palmar arch lies on the proximal ends of the metacarpals

and interossei and is covered by the flexor tendons and

adductor pollicis. Most anatomists have found the deep arch

to be quite variable in size and usually inversely proportional

to the caliber of the superficial arch and its branches.

The deep palmar arch is represented by two groups: group

I, in which the arch is complete (97%), and group II, in which

the arch is incomplete (3%). Coleman and Anson defined a

complete arch as one formed by anastomoses of the contributing arteries, or when the ulnar artery extends to the

thumb and index finger. An incomplete arch occurs when the

contributing arteries do not anastomose or when the ulnar

artery fails to reach the thumb and index finger (25).

Group I: Complete Arch (97%) (Fig. 10.18)

Type A (34.5%). The deep volar arch is formed by the

main stem of the radial artery, which joins the superior

ramus of the deep branch of the ulnar artery.

Type B (49%). The deep palmar arch is formed by the

main stem of the radial artery, which joins the inferior

ramus of the deep branch of the ulnar artery.

Type C (13%). The deep palmar arch is formed by the

main stem of the radial artery, which joins both the inferior

and superior branches of the deep branch of the ulnar

artery.

Type D (0.5%). The deep palmar arch is formed by the

superior deep branch of the ulnar artery, which joins an

enlarged superior perforating artery of the second interspace.

Group II: Incomplete Arch (3%) (Fig. 10.19)

Type A (1.5%). The inferior deep branch of the ulnar artery

joins the perforating artery of the second interspace. The deep

supply to the thumb and radial side of the index is derived

from the deep palmar branch (main stem) of the radial artery.

Type B (1.5%). The deep arterial supply to the thumb

and index are from the deep palmar branch (main stem)

of the radial artery, which joins with the perforating

artery of the second interspace. The arch is not complete

because the deep branch of the ulnar artery ends in an

anastomosis with the perforating artery of the third interspace.

552 Regional Anatomy

FIGURE 10.16. The six patterns of the

dorsal carpal arch, after Coleman and

Anson (25). See text for details.

Branches of the Deep Palmar Arch

Proximal. These are the recurrent carpal vessels, two or

three in number, which course proximally to end in the palmar carpal rete or join with the palmar carpal branches of

the palmar interosseous artery (see Fig. 10.17). Coleman

and Anson found these vessels in all specimens studied, but

in only 5% could an anastomosis be demonstrated by dissection between these small vessels and the carpal branches

of the palmar interosseous artery.

Distal. These include the so-called princeps pollicis, the

artery to the radial side of the index finger, which may arise

in common with the princeps pollicis and the three PMAs

(see Fig. 10.17). There is considerable variation in the

PMAs as to number, course, and area of supply, and in

Coleman and Anson’s series these arteries were found to be

the most variable vessels in the hand.

Palmar Metacarpal Arteries

Because of the extreme variability in the PMAs, Coleman

and Anson put forth the following conceptual guides: (a)

that a palmar metacarpal vessel is one that arises from the

deep arch and extends at least as far distal as the MCP

joint; (b) that the large artery to the thumb is considered

to be the first PMA, the large vessel that courses along the

palmar aspect of the second metacarpal bone is the second PMA, and these vessels may arise from a common

trunk; and (c) the remainder of the vessels are best considered on the basis of type and number—the smallest

10.1 Palmar Hand 553

FIGURE 10.17. Deep palmar arch and its branches. At the base of the small finger metacarpal,

the main stem of the radial artery anastomoses with the deep branch of the ulnar artery to form

the deep palmar arch. See text for details of branching. RC, recurrent carpal artery; PMA, palmar

metacarpal artery; PF, perforating branch; asterisk indicates anastomosis with superficial arch.

number of vessels found was three and the largest was six

(25).

One consistent feature was found: the first and second

PMAs both were present in 95% of specimens; in only 2

instances of the 100 hands was the first PMA absent, and in

only 3 cases was the second PMA absent. In no specimen

were both vessels absent. Coleman and Anson also found that

the first and second PMA almost always traveled over the palmar surfaces of the corresponding bones rather than over the

adjacent interosseous muscles, as classically described. The

remaining members of the PMAs were inconstant in their

relationship to the interspaces, the metacarpals, or the

interosseous muscles. Frequently, two metacarpal vessels

arose in the same interosseous space but passed distally to

adjacent MCP joint capsules or adjacent interdigital webs, or

both. Thus, the assignment of a specific number to the PMAs

is difficult except for the first and second, which are comparatively constant. Coleman and Anson classified the third,

fourth, and fifth PMAs based on number and type (25).

Type 1 (30%)

The PMA joins the appropriate common palmar digital

artery, as is classically described.

Type 2 (60%)

The artery ends in the capsule of the MCP joint.

Type 3 (10%)

The vessel bifurcates at the level of the head of the

metacarpal and joins with two separate common palmar

digital arteries or their branches.

554 Regional Anatomy

FIGURE 10.18. Patterns of deep volar (radial) arterial arch,

types A through D, group I, complete arch, after Coleman and

Anson (25).

FIGURE 10.19. Patterns of deep volar (radial) arterial arch,

types A and B, group II, incomplete arch, after Coleman and

Anson (25).

Dorsal Metacarpal Arteries

These are perforating branches, three in number, from the

region of the second, third, and fourth interspaces, that pass

to the dorsum of the hand to join their respective dorsal

metacarpal arteries. Coleman and Anson dissected 25 hands

to study these structures, and 4 types were identified.

Type 1

These vessels, usually three in number, arise either from the

deep palmar arch or, less frequently, from a common trunk

with a PMA. They pass dorsally through the intermetacarpal spaces to join or form entirely the corresponding dorsal metacarpal artery.

Type 2

Just proximal to the metacarpal head the PMA sends a perforating vessel to the dorsum that joins the corresponding

dorsal metacarpal artery.

Type 3

A vessel from the proper palmar digital artery passes dorsally to join the corresponding dorsal metacarpal artery or

one of its digital branches.

Type 4

This is the least frequent pattern and consists of vessels arising from the deep palmar arch that pass obliquely through

the interosseous muscles to join the corresponding dorsal

metacarpal artery near the MCP joint (25).

Ulnar Artery

The ulnar artery approaches the wrist just beneath and

radial to the FCU tendon (Fig. 10.20). It is radial to the

ulnar nerve and is in the interval between the FCU and the

flexor digitorum superficialis (FDS) to the ring and small

fingers. It enters the hand accompanied by the ulnar nerve

on top of the transverse carpal ligament (TCL) and radial to

the pisiform bone. This entryway, called the loge de Guyon

or Guyon’s canal, is a triangular space.

Guyon’s canal begins at the proximal edge of the palmar

carpal ligament and extends to the fibrous arch of the

hypothenar muscles. Beginning from proximal to distal, the

roof of the canal is formed by the palmar carpal ligament

and the palmaris brevis muscle. The floor is formed by the

TCL, the pisohamate and pisometacarpal ligaments, and

the opponens digiti minimi (ODM). The ulnar wall is composed of the FCU, the pisiform, and the abductor digiti

minimi (ADM). The radial wall is formed by the tendons

of the extrinsic flexors, the TCL, and the hook of the

hamate (27). The average length of Guyon’s canal is 27 mm

(range, 20 to 34 mm) (27). The ulnar nerve and artery

branches in this region are covered by the palmaris brevis

muscle and surrounded by a thick fat pad.

Ulnar Artery Branching and Course

Konig et al., in a study of 23 cadaver hands, noted that the

ulnar artery in 17 hands after entering Guyon’s canal gave

off a small branch that accompanied the deep motor branch

of the ulnar nerve but ended in the hypothenar muscles

(28) (see Fig. 10.20). In these 17 cases, the deep branch of

the ulnar artery was given off more distally and entered the

retrotendinous mid-palmar space between the flexor sheath

of the small finger and the flexor digiti minimi (FDM), and

thus joined the course of the deep motor branch of the

ulnar nerve at a more distal level. The main trunk of the

ulnar artery continued distally after this branch to form the

superficial palmar arch. In four of the six remaining hands,

the deep motor branch was accompanied by the deep palmar branch of the ulnar artery, and in these four cases no

other branch was found to enter the mid-palmar space distally (28). Thus, the origin of the deep palmar arterial

branch most often was distal to Guyon’s canal.

Lindsey and Watamull identified 2 patterns of ulnar

artery branching in Guyon’s canal in a study of 31 cadaver

hands (27). All arterial branches to the hypothenar muscles

occurred in Guyon’s canal in 30 of 31 cases. Only one arterial branch to the hypothenar muscles occurred distal to the

canal.

In type 1 (17 of 31 cases), a major vascular branch passed

from the ulnar artery to the hypothenar muscles palmar to

the ulnar nerve. The average distance from the proximal

margin of the pisiform to the branch was 14 mm (range, 6

to 25 mm; see Fig. 10.14).

In type 2 (6 of 31 cases), the vascular branch passed palmar to the motor branch and dorsal to the sensory branch

by an average distance of 15.2 mm from the proximal margin of the pisiform (range, 4 to 32 mm). There was no identifiable axial pedicle in the remaining eight cases.

No arterial branch was noted to travel with the motor

branch of the ulnar nerve around the hook of the hamate in

any specimen. The average distance between the

hypothenar muscle artery and the nearest hypothenar nerve

branch was 8.3 mm (range, 0 to 22 mm) (27).

These two studies are in agreement with those of

Farabeuf, Landsmeer, and Zeiss et al. (29–31) and indicate

that the first ulnar artery branch in Guyon’s canal most

often supplies the hypothenar muscles and the deep branch

of the ulnar artery that joins the radial artery to form the

deep palmar arch usually is distal to Guyon’s canal. Also, the

motor branch of the ulnar nerve that travels around the

hook process of the hamate usually is not accompanied by

an artery.

The deep branch of the ulnar artery most often enters

the depths of the hand between the flexor tendon sheath of

the small finger and the FDM, to a position deep to the

interosseous fascia, where it joins the main stem of the

radial artery to form the deep palmar arch. The palmar digital artery to the ulnar side of the small finger arises a few

millimeters distal to the origin of the deep branch. As the

10.1 Palmar Hand 555

556 Regional Anatomy

FIGURE 10.20. The ulnar artery and Guyon’s canal. The ulnar artery enters the hand accompanied by the ulnar nerve on top of the transverse carpal ligament and radial to the pisiform bone.

main stem of the ulnar artery turns radially to cross the

palm as the superficial palmar arch, it gives rise to three

common palmar digital arteries that go to the three digital

web spaces, where they divide into proper digital arteries. In

their study of this region, Coleman and Anson observed

that two deep branches of the ulnar artery were present in

63.5% of their dissections (25). The superior branch was

present in all specimens and accompanied the ulnar nerve

deep to the origins of the FDM muscle. However, in half of

the specimens this branch ended in the hypothenar muscles

and did not join the deep arch. According to Coleman and

Anson, the inferior branch was present in 63.5% of the 200

specimens and invariably took part in formation of the deep

arch. This inferior ramus did not follow the course of the

ulnar nerve, but passed superficial to the FDM and deep to

the flexor tendons. Occasionally, both of these vessels

joined the deep arch (25).

Author’s Comment

Our dissections of Guyon’s canal and the anatomic zones

distal to this region indicate that the observations of Konig

et al. (28) and Lindsey and Watamull (27) are probably a

more accurate interpretation of the anatomy in this region.

Superficial Palmar Arch

This arch lies just beneath the palmar fascia and on top of

the superficialis tendons, and may be complete or incomplete (Fig. 10.21; see Fig. 10.14). Of the 650 hands in Coleman and Anson’s study, 510 or 78.5% possessed complete

arches, and 5 types were identified.

Coleman and Anson defined a complete arch as one

formed by anastomoses of the contributing arteries, or in

which the ulnar artery extended to the thumb and index

finger (25).

Group I: Complete Arch. Type A (34.5%). The classic or

textbook description of the superficial arch is formed by the

superficial palmar branch of the radial artery (SPBR) and

the main stem of the ulnar artery.

Type B (37%). The most common formation of the superficial arch is entirely from the ulnar artery.

Type C (3.8%). The superficial arch is formed from the

ulnar artery and an enlarged median artery.

Type D (1.2%). The superficial arch is formed by the

SPBR, the main stem of the ulnar artery, and a persistent

median artery.

Type E (2.0%). This type consists of a well formed arch

begun by the ulnar artery and completed by a large vessel

derived from the deep arch that comes to the superficial

level at the base of the thenar eminence to join the ulnar

artery.

In no specimen did a palmar interosseous artery take

part in the formation of the superficial palmar arch, and no

example of complete absence of the arch was found.

Group II: Incomplete Arch. Coleman and Anson’s definition of an incomplete arch is when the contributing arteries do not anastomose or when the ulnar artery fails to reach

the thumb and index.

Type A (3.2%). Although both the SPBR and the main

stem of the ulnar artery supply the palm and fingers, they

fail to anastomose and thus the arch is incomplete.

Type B (13.4%). The ulnar artery is the superficial palmar

arch but the arch is incomplete in the sense that it does not

provide any blood supply to the thumb and index finger.

Type C (3.8%). The superficial arch receives contributions

from both the median and ulnar arteries but without anastomosis.

Type D (1.1%). The radial, median, and ulnar arteries all

give origin to the superficial vessels but do not anastomose.

Branches of the Superficial Palmar Arch

In a study of 265 specimens, Coleman and Anson classified

7 different patterns of the common palmar digital arteries

without regard to the peculiarities of the superficial arch

(Fig. 10.22; see Fig. 10.14).

Type 1 (77.3%). This type contains four common palmar

digital arteries, and in all cases a vessel supplying the ulnar

side of the thumb and the radial side of the index finger.

The remaining three arteries pass to the webs of the second,

third, and fourth interspaces.

Type 2 (8.8%). This type has three common palmar digital arteries that pass to the webs of the second, third, and

fourth interdigital spaces.

Type 3 (6.4%). In addition to three common palmar digital arteries noted in type 2, an artery passes to the thumb,

where it joins with or replaces one of the arteries of the

thumb but does not send a branch to the index.

Type 4 (1.9%). This type has three common palmar digital arteries that pass to the first, second, and fourth interspaces but not to the third.

Type 5 (3.4%). This type has three common palmar digital arteries that pass to the second, third, and fourth interspaces, as in type 2, and a branch to the lateral side of the

index finger.

Type 6 (1.5%). This type has only two common palmar

digital arteries that pass to the second and third interspaces.

10.1 Palmar Hand 557

558 Regional Anatomy

FIGURE 10.21. The incidence, formation, and patterns of complete (A) and

incomplete (B) superficial palmar arches, after Coleman and Anson (25).

A

B

Type 7 (0.7%). This type has common palmar digital

arteries only to the third and fourth interspaces (25).

Based on their findings, Coleman and Anson made the

following generalizations: (a) the vessel to the first interspace is sufficiently constant to be recognized as the first

common palmar digital artery; (b) when a common palmar

digital artery is small in caliber, the corresponding PMA

from the deep arch is enlarged; (c) the area of supply of an

absent branch of the superficial arch may be replaced by a

PMA; and (d) branches of the median artery or the superficial branch of the radial artery rarely directly supply the

medial side of the hand.

Persistent Median Artery

A persistent median artery may descend into the palm and

take part in the formation of the superficial palmar arch.

Such a finding was noted in 64 or 9.9% of Coleman and

Anson’s 650 specimens (25). The frequency of occurrence

in other series was Jaschtschinski, 7.5% of 200 specimens;

Tandler, 16.1% of 160 specimens; Adachi, 8% of 200 specimens; and Gray, 1.1% of 452 specimens (32–35). According to Coleman and Anson, these variations in frequency

can be explained in part by the observation that the median

artery often joins the superficial arch as a fibrotic thread or

a very small vessel that is barely detectable, and such cases

would not be included in a series. When the median artery

does join the superficial arch, it replaces no more than the

contribution of the radial artery to the arch. This is in keeping with the developmental sequence because the radial

artery replaces the median during development (25).

Vessel Lumen Diameters

Gellman et al. in an injection study of 45 hands noted the

arterial lumen diameters listed in Table 10.3 (36).

10.1 Palmar Hand 559

FIGURE 10.22. Branching of the superficial palmar arch, after Coleman and Anson (25).

TABLE 10.3. AVERAGE LUMEN DIAMETERS OF THE

ARTERIES IN THE HAND

Average Lumen Range

Vessel Diameter (mm) (mm)

Radial 2.6 2.3–5

Ulnar 2.5 1.4–4.5

Superficial arch 1.8 1–3

Deep arch 1.5 1–2.3

Common palmar digital 1.6 1–2

Common palmar metacarpal 1.2 1–2

Arterial Supply of the Fingers

Coleman and Anson noted that several generalizations

could be made regarding the arterial supply to the fingers.

There are three arterial sources to each finger: (a) the common palmar digital, (b) the palmar metacarpal, and (c) the

dorsal metacarpal. Two proper digital arteries are formed,

each of which supplies the adjacent sides of the fingers. In

most instances, the common palmar digital arteries are the

source of these digital arteries, but it is not uncommon for

a PMA to supplant a common palmar digital artery. In rare

instances, principally in the first and second interspaces, the

main supply may come from the dorsal metacarpal vessels.

The dorsal metacarpal arteries, joined by perforating

branches from the deep palmar arch or PMAs that pass

through and supply the interosseous muscles, pass distally

adjacent to the MCP joints to become the dorsal digital

arteries. When these vessels terminate near the neck of the

proximal phalanges, the terminal supply is taken over by the

proper palmar digital arteries (25).

Arterial Supply of the Digital Web Spaces

The following generalizations were given by Coleman and

Anson about the arterial supply to the various web spaces.

First Interspace

The arterial supply to the first interspace usually is derived

from the deep arch, either from the first PMA alone or from

both the first and second PMAs.

Second Interspace

This is derived approximately equally from the second

PMA or the second common palmar digital artery, thus

being shared almost equally by the superficial and deep

arches.

Third and Fourth Interspaces

These spaces are primarily supplied by the common palmar

digital branches of the superficial arch.

Thus, the thumb and index finger and the radial side of

the middle finger are supplied by the deep arch or radial

artery. The medial side of the middle finger, and the ring

and small fingers are supplied almost exclusively by the

superficial arch and the ulnar artery. The middle finger

therefore represents the dividing point between the supply

zones of the deep and superficial arches (25).

Digital Arterial Branches and Arches

In a study of 141 digits, Strauch and de Moura identified the

following arterial branches in the fingers (37) (Fig. 10.23).

Palmar Digital Arteries

The palmar branches of the digital arteries average 4 from

each side at the level of the proximal and middle phalanges,

but there were as many as 7 in one specimen from this study

of 141 digits. When there are more than four branches, they

usually arise from the dominant vessel.

Dorsal Digital Arteries

The dorsal branches of the digital arteries are of four types:

(a) condylar vessels, (b) metaphyseal vessels, (c) dorsal skin

vessels, and (d) transverse palmar arches.

First Set of Dorsal Digital Arteries. The first condylar

branch (a) to the head of the metacarpal may arise from the

common or proper digital vessel. It was present in 60% of

the dissections, varies in size from 0.1 to 0.5 mm, and occasionally shares a common origin with the metaphyseal vessel. The first metaphyseal vessel (b), which arises at the base

of the proximal phalanx, measures between 0.1 and 0.2

mm. The first dorsal skin vessel (c), in the middle portion

of the proximal phalanx, is a large branch that supplies the

overlying skin of the proximal phalanx. This vessel measures

0.4 to 0.5 mm in external diameter and was absent on one

side in 5% of the 141 digits studied. The proximal transverse arch (d), at the neck of the proximal phalanx and at

the level of the C1 pulley, measures between 0.3 and 0.6

mm. These vessels from the opposing digital arteries join

centrally to form a slightly peaked arch. Branches from this

arch go to the vinculum longus and brevis, the profundus

and superficialis tendons, the dorsal skin proximal to the

PIP joint, and the distal metaphysis of the proximal phalanx; a branch that crosses the PIP joint goes to the proximal metaphysis of the middle phalanx.

Second Set of Dorsal Digital Arteries. In the middle phalanx, the second condylar branch (a) supplies the base of the

middle phalanx, and the major portion of the vessel supplies

the skin over the PIP joint. This condylar vessel was present

in 80% of the specimens and averages 0.2 to 0.5 mm in

external diameter. The second metaphyseal branch (b) is a

constant vessel that goes to the proximal metaphysis of the

middle phalanx; it is the largest of the three metaphyseal vessels at 0.25 ± 0.05 mm. At the mid-portion of the middle

phalanx, the second dorsal skin vessel (c) arises and supplies

most of the dorsal skin over the middle phalanx. It was present in all dissected specimens and is 0.45 mm in average size.

The second transverse palmar arch (d) arises at the neck of

the middle phalanx in relationship to the third cruciform

(C3) pulley, was present in 90% of the dissections, and is 1.5

times the size of the proximal arch, at an average size of 0.85

mm. Branches from this arch include the distal vinculum vessel to the profundus tendon; a branch to the distal metaphysis of the middle phalanx that goes on to supply the skin

over the DIP joint as well as continuing on to join the proximal matrix arch dorsally at the level of the proximal growth

plate of the nail; and, finally, small branches that go across the

DIP joint to nourish the proximal metaphyseal area of the

distal phalanx.

560 Regional Anatomy

Third Set of Dorsal Digital Arteries. The third condylar

vessel (a) supplies the condylar area of the distal end of the

middle phalanx and measures 0.14 mm. It originated as a

common vessel with the metaphyseal vessel in 20% of the

specimens. The proximal metaphyseal vessel (b) was uniformly present and averages 0.14 mm. The third dorsal skin

vessel (c) arises just proximal to the distal transverse palmar

arch and courses dorsally to form the proximal matrix arch

at the level of the proximal growth plate of the nail. This

vessel measures between 0.2 and 0.4 mm. The proximal

matrix arch at the DIP joint area is joined by the two vessels that originally arose from the middle palmar arch and

traveled dorsally and distally. These vessels average 0.25 mm

and unite on the dorsal surface with the proximal matrix

arch. The digital vessels then turn centrally to join each

other to form the distal transverse arch (d). Extending from

this arch in a longitudinal fashion are three relatively large

vessels averaging 0.58 mm that travel to the distal aspect of

the pulp and turn dorsally to join with the distal matrix

arch. Arising from the two lateral longitudinal vessels on

either side or, more commonly (60%), from two more centrally placed longitudinal vessels is a branch that goes dorsally on either side. This branch averages 0.48 mm and, as

it nears the dorsal surface, it divides to join its counterpart

on the opposite side, thus forming the middle matrix arch

at the level of the lunula and the distal matrix arch that lies

10.1 Palmar Hand 561

FIGURE 10.23. Digital arterial branches and arches,

after Strauch and de Moura (37). There are three sets

of four dorsal branches of the digital arteries: A:

condylar vessels; B: metaphyseal vessels; C: dorsal skin

vessels; D: transverse palmar arches. See text for

details.

at the level of the distal third of the nail matrix. These

arches average 0.29 mm in size.

Digital Vessel Diameters

Strauch and de Moura made some practical observations on

the external diameter of the digital vessels, and these measurements are given in Table 10.4.

These authors noted that of the two digital vessels in the

thumb and index and long fingers, the ulnar vessel almost

always is larger, whereas the radial vessel almost always is

larger in the ring and small fingers. The common digital

vessel to the third web space divided into branches that

were large on both sides of the web.

Clinical Significance

Strauch and de Moura noted several clinical implications

from their study:

1. A high level of consistency in the distribution and location of digital vessels was seen, not previously described.

2. In digital amputations of the thumb and index and long

fingers, the surgeon should look for the ulnar vessel first

because it is the larger of the two. The reverse is true for

the ring and small fingers.

3. The middle and distal transverse arches are consistently

large (almost 1 mm) and may be used for arterial vessel

repairs either proximally or distally; furthermore, these

two arches are easily located because of their uniform

relationship to the cruciate ligaments and the profundus

tendon insertion (37).

Further perspective on the importance of transverse digital arches is given by reported experiences with replantation for transmetacarpal hand amputation. Successful revascularizations of all the fingers and thumb have been

reported by attaching a single common digital vessel to a

proximal arterial source. The ability of one common digital

artery to revascularize all the fingers and thumb was the

result of retrograde flow through the transverse arches

(38,39).

Arterial Anatomy of the Thumb and

Index Finger

The arterial anatomy of the thumb and radial side of the

index finger is discussed in this section, and the reader will

soon note striking variations in reported series that have

addressed this area of arterial anatomy (23,24,40). It therefore seems appropriate to reiterate some of the observations

of Coleman and Anson (25) previously cited in this chapter, and specifically to discuss their observations on the

PMAs. Coleman and Anson stated that there was considerable variation in the PMAs as to number, course, and area

of supply, except for the first and second PMA. They noted

that the large artery to the thumb is considered to be the

first PMA, that the large vessel that courses along the palmar aspect of the second metacarpal bone is the second

PMA, and that these vessels may arise from a common

trunk. One consistent feature was found: The first and second PMAs both were present in 95% of specimens; in only

2 instances of 100 hands studied was the first PMA absent,

and in only 3 cases was the second PMA absent. In no specimen were both vessels absent. Coleman and Anson also

found that the first and second PMA almost always traveled

over the palmar surfaces of the corresponding bones rather

than over the adjacent interosseous muscles, as classically

described. Recognition of the relative constancy of the first

and second PMA, which in general represent the stem vessels to the thumb and index finger, allows us now to address

the specifics of the arterial supply to the thumb and index

finger. This topic has attracted much attention, and recent

studies have emphasized differences from the classic

anatomic literature in the arrangement and relative dominance of the arterial vessels of the thumb, and specifically

that the so-called princeps pollicis artery may not be the

major vessel to the thumb, and in fact may be a misnomer.

Three studies are reviewed: the first by Parks et al., the

second by Ames et al., and the third by Earley (23,24,40).

Findings of the Parks and Colleagues Study

In a study of 50 embalmed hands, Parks and coworkers

found that the first PMA was the principal artery of the

thumb in 80% of their dissections. They noted that the first

PMA was a major branch of the deep radial artery and closely

corresponded to the PMA of the other fingers. The princeps

pollicis artery divided at the level of the MCP joint and deep

to the flexor pollicis longus (FPL) tendon into radial and

ulnar digital arteries. The radial index artery arose from the

princeps pollicis in 50% of the dissections. Variations in the

so-called princeps pollicis artery were noted in 25%, but

these variations were not described. The first dorsal

metacarpal artery was the main artery to the thumb in 14%.

It originated before the radial artery pierced the first DI muscle and passed to the thumb dorsal to the DI muscle. A

branch from the second PMA formed the main artery to the

562 Regional Anatomy

TABLE 10.4. DIGITAL VESSEL DIAMETERS

Finger Vessel Location Size (mm)

Index Radial Base proximal phalanx 1.4 ± 0.10

Ulnar 1.8 ± 0.15

Radial Base distal phalanx 0.76 ± 0.15

Ulnar 0.86 ± 0.10

Ring and Radial MCP joint 1.75 ± 0.15

small Just distal to DIP joint 0.95 ± 0.15

Ulnar MCP joint 1.35 ± 0.2

Just distal to DIP joint 0.85 ± 0.1

DIP, distal interphalangeal; MCP, metacarpophalangeal.

thumb in 6%. In 20%, a significant arterial contribution was

made by the superficial palmar vessels (40).

Findings of the Ames and Colleagues Study

In a study of 39 fresh cadaver hands, Ames et al. identified

what they considered to be the dominant vessel of the

thumb and radial side of the index based on relative size,

and described five patterns of arterial anatomy in the

thumb (23) (Fig. 10.24).

Vascular Pattern A: Incidence 21/39 (54%)

Both superficial and deep vessels were noted in the first

web. The origin of the superficial vessel was from the superficial palmar arch in 18 specimens, from the SPBR in 2

specimens, and from the median artery in 1 specimen. The

deep vessel originated from the first PMA in 19 of 21 specimens, and from the dorsal metacarpal artery in the other 2

specimens. The superficial and deep vessels joined, giving a

radial digital artery to the index and an ulnar digital to the

thumb. In 20 of the 21 specimens, the superficial and deep

vessels joined together in the first web space. The SPBR was

absent in 8 of the 21 specimens. Thus, it was clear that this

pattern did not have a dominant or princeps pollicis artery.

Vascular Pattern B: Incidence 3/39 (8%)

The SPBR was the dominant vessel. In two specimens it supplied both sides of the thumb, together with the radial side of

the index finger. In the third specimen, the SPBR supplied a

vessel to the first web space with bifurcation only to the ulnar

side of the thumb and the radial side of the index finger. The

radial side of the thumb was supplied by the radial artery.

Vascular Pattern C: 7/39 (18%)

The first palmar metacarpal was the largest or dominant

vessel, and in three of these there did not appear to be a

10.1 Palmar Hand 563

FIGURE 10.24. A–E: Patterns of arterial supply to the thumb, after Ames et al. (23).

A

C, D E

B

connection between the superficial and deep systems. The

authors noted that these three specimens were the only

specimens in their study that corresponded to the classic

description shown in anatomic textbooks (in this instance,

Gray’s Anatomy, 28th ed., 1969).

Vascular Pattern D: 3/39 (8%)

In three specimens, a large dorsal metacarpal artery was

considered to be the dominant vessel. In two instances there

was an anastomosis with the superficial system.

Vascular Pattern E: 5/39 (13%)

In 5 of 39 specimens there was no dominant vessel, and in

only 1 specimen was there an anastomosis between the

superficial and deep vessels. The deep vessel came from the

dorsal metacarpal artery, and in all five specimens the superficial system supplied the ulnar side of the thumb, whereas

the deep system supplied the radial aspect of the thumb. In

one of these specimens the first PMA entered the FPL

sheath and divided into radial and ulnar digital vessels.

Other Findings of the Ames and Colleagues Study

In contrast to the dorsal branch of the radial artery, which,

after exiting the snuff-box, always passed through the two

heads of the first DI muscle, the SPBR either remained

deep in the substance of the thenar muscles or passed over

them. Variously, it could supply both aspects of the thumb

and the radial aspect of the index finger, become a vessel to

the first web space, participate in the formation of the

superficial arch, or terminate in the skin of the first web

space, in the thenar muscles, or as a radial digital vessel to

the thumb.

Summary and Conclusions of the Ames and Colleagues

Study

These findings indicate that the arterial supply in the hand

is variable. Five patterns were noted based on vessel dominance. The most common pattern revealed a superficial and

deep system that frequently connected within the first web

space. The superficial palmar arch was complete in only

24% of this study group. The so-called princeps pollicis or

first PMA was dominant in only 18% of the specimens.

Findings of the Earley Study

The study by Earley of the arterial supply of the thumb and

index finger in 20 fresh and injected cadavers made the following observations (24).

The Superficial Arch

The superficial or main stem branch of the ulnar artery may

give rise to a common digital artery to each web space (4 of

20 dissections), and in 3 of these 4 specimens the first web

space common digital artery was the only supply to the ulnar

side of the thumb and the radial side of the index finger.

The Superficial Palmar Branch of the Radial Artery

1. The SPBR can vary from supplying only small branches

to the carpal ligament and thenar muscles to providing

the main blood to the thumb and radial side of the index

finger (Fig. 10.25);

2. The SPBR gave origin to (a) proximal (20 hands) and

distal (14 hands) thenar muscle branches; (b) carpal ligament branches (6 hands); (c) APB branches (14 hands),

usually manifested as a large branch running superficially over the APB toward the radial sesamoid at the

thumb MCP joint and often (7 of 14) communicating

with the radial digital artery of the thumb at the socalled sesamoid sink; in 2 hands it even formed the

radial palmar digital artery of the thumb; and (d) a

branch joining with the superficial and main stem of the

ulnar artery to form the superficial palmar arch (12 of

20 hands). In half of these, the communicating branch

gave origin to either the radial palmar index artery or to

the common digital arteries to the first and second webs.

Thus, in 6 of 20 hands, the SPBR supplied a significant

part of the circulation to the radial one-half of the hand.

The two arteries forming the superficial arch of the hand

were noted to contribute significantly to the thumb and

index finger blood supply.

The First Palmar Metacarpal Artery

1. This artery was present in all hands examined by Earley

and was the first branch of the radial artery on its return

to the palm (Fig. 10.26).

2. In three hands it shared a common origin with the second PMA.

3. The usual course (18 of 20 hands) was on the ulnar side

of the thumb metacarpal on the interosseous muscle

belly, after which it passed deep to the FPB (deep head)

and exited in the interval between the adductor and the

deep head of the FPB.

4. Its classic division into digital arteries at approximately

this level beneath the FPL tendon was seen in only 8 of

the 20 hands, and in 2 hands the first PMA passed deep

to the deep head of the FPB and oblique head of the

adductor pollicis and emerged between the two adductor heads at the ulnar sesamoid.

5. The first PMA followed the usual patterns of arterial

variation from (a) one of least expression, where it supplied only a communicating branch to the palmar digital arteries; to (b) one of intermediate expression, where

it gave origin to only one digital artery; and (c) one of

greatest expression, where it gave rise to both digital

arteries.

Branches of the First Palmar Metacarpal Artery

Branches of the first PMA included the following:

1. The thumb palmar digital arteries. In 8 of 20 hands,

both palmar digital arteries originated from the first

564 Regional Anatomy

10.1 Palmar Hand 565

FIGURE 10.25. A, B: Patterns of

branching of the superficial palmar

branch of the radial artery, after Earley’s study of 20 hands (24).

FIGURE 10.26. The first palmar metacarpal artery

(PMA), based on Earley’s study of 20 hands (24). This

artery is the first branch of the radial artery (17 of 20

hands) on its return to the palm, and its usual course is

shown here (A); in 3 hands, it shared a common origin

with the second PMA. Its usual course (18 of 20 hands)

is on the ulnar side of the thumb metacarpal on the

interosseous muscle belly, it then passes deep to the

flexor pollicis brevis (FPB; deep head) and exits in the

interval between the adductor and the deep head of

the FPB. Its classic division as shown here into digital

arteries at approximately this level beneath the flexor

pollicis longus tendon was seen in only 8 of the 20

hands, and in 2 hands (B) the first PMA passed deep to

the deep head of the FPB and the oblique head of the

adductor pollicis and emerged between the two adductor heads at the ulnar sesamoid.

A B

A

B

PMA, and in 11 of 20 hands, the parent artery gave rise

to only 1 palmar digital artery and in one hand to none.

2. Branches at the level of the neck of the thumb metacarpal. These were constant, with vessels curving around

the neck to supply dorsal structures and the MCP joint.

3. Muscle branches to the adjacent thenar muscles.

4. Terminal communicating branches. These were seen in

8 of 20 hands, and in 7 of these there was a branch communicating with the opposite palmar digital artery while

the main vessel formed the other palmar digital artery.

In the eighth hand, no palmar digital branch was

formed, and the terminal branch of the first PMA was

only a small communicating branch with the ulnar

artery.

The Thumb Palmar Digital Arteries

In 18 of 20 hands, the ulnopalmar artery (average external

diameter, 1.8 mm) was larger than the radiopalmar digital

artery (average external diameter, 1.1 mm), ranging from

one-fourth to three times larger. In the remaining two

hands, the palmar digital arteries were the same size, and in

one hand the radiopalmar was three times larger than its

counterpart.

Ulnopalmar Digital Artery

The ulnopalmar digital artery was a terminal branch of the

first PMA (so-called princeps pollicis) in only half of the

specimens. In 6 of the 10 specimens it followed a course

emerging from the deep surface of the FPL tendon and

curving over the insertion of the adductor at the ulnar

sesamoid to follow the flexor sheath on its ulnar aspect. Earley named this configuration the pre-adductor type. In the

remaining four hands, the artery followed a course deep to

the adductor and thus was named the post-adductor type.

The vessels forming the other 10 ulnopalmar digital arteries were:

1. One of the terminal branches of the main stem of the

ulnar (three hands)

2. A branch of the superficial palmar radial artery (three

hands)

3. Equal contributions of the first PMA and terminal

superficial arteries (one hand)

4. Equal contributions of the SPBR and terminal branch of

the main stem of the ulnar (one hand)

5. A large first dorsal metacarpal artery (one hand)

6. A hypertrophied ulnodorsal digital artery (one hand)

In spite of its various origins, once it reached the ulnar

sesamoid the ulnopalmar digital artery followed a superficial course in all hands.

Radiopalmar Digital Artery

1. The radiopalmar digital artery was a branch of the first

PMA in 18 of 20 hands.

2. Its initial course was deep to the FPL tendon, then curving over the free margin of the superficial head of the

FPB to the radial sesamoid.

3. In 2 of the 18 hands, the first PMA reached the radial

sesamoid by emerging between the adductor heads, and

then gave origin to the radiopalmar digital artery, which

had to reach the radial side of the thumb by passing

beneath the FPL in the region of the first annular (A1)

pulley.

4. In the remaining two hands, the radiopalmar digital

artery arose from the APB branch of the SPBR.

Arches of the Thumb Palmar Digital Arteries

Two arches were present between the thumb palmar digital

arteries (Fig. 10.27):

1. The digitopalmar arch was seen in all hands at the level

of the neck of the proximal phalanx in the retrocondylar

recess and beneath the oblique pulley. It gave branches

to the FPL through the vincula brevia, the palmar plate,

the interphalangeal joint, and the flexor sheath.

2. The pulp arch lay in the recess just proximal to the tuft

of the distal phalanx and gave off multiple branches supplying the pulp and nail bed.

Index Radiopalmar Digital Artery

Three main origins for this artery were seen (Fig. 10.28):

1. A branch of the main stem or superficial ulnar artery (5

of 20 hands)

2. A branch of the second PMA (5 of 20 hands)

3. A branch of the SPBR (5 of 20 hands)

First Dorsal Metacarpal Artery

The first dorsal metacarpal artery was present in all hands

and originated from the radial artery just distal to the EPL

tendon (see Fig. 10.26). Three types were noted:

1. A superficial and axial fascial vessel parallel to the second

metacarpal and overlying the first dorsal interosseous

muscle (15 of 20 hands)

2. A deep or muscular vessel to the ulnar head of the first

DI muscle that followed a buried course in the groove

between the muscle origins and the second metacarpal,

but emerged after a variable distance to follow a more

superficial fascial course (3 of 20 hands)

3. A combination type consisting of both fascial and muscle types (2 of 20 hands; 2 branches of 1 vessel in one

hand, but 2 separate vessels in the other)

The ulnodorsal thumb digital artery originated from the

first dorsal metacarpal artery in 6 of 20 hands.

Second Dorsal Metacarpal Artery

The second dorsal metacarpal artery was present in 19 of 20

hands.

566 Regional Anatomy

1. It was smaller than the first dorsal metacarpal artery in

12 hands, the same size in 1 hand, and larger in 6 hands.

2. Its origin was variable, but it usually arose from the dorsal carpal arch (15 of 20 hands), then crossed under the

extensor indicis proprius to reach the second DI muscle,

where it followed a superficial course to reach the skin of

the second web.

Dorsal Thumb Digital Arteries

These vessels were extremely variable, and were small or

absent if the dorsal branches from the first PMA were large.

Ulnodorsal Digital Artery

The ulnodorsal digital artery was absent in six hands, in six

others it was branch of a fascial-type first dorsal metacarpal

artery, and in six others it was a branch of the radial artery

distal to the EPL tendon before the origin of the first dorsal metacarpal artery.

Radiodorsal Digital Artery

The radiodorsal digital artery was absent in 6 hands and

was represented by 1 vessel in 11 hands and 2 vessels in 3

hands. In all hands, the vessels originated from the radial

10.1 Palmar Hand 567

FIGURE 10.27. Arches of the thumb palmar digital

arteries. The digitopalmar arch is at the level of the neck

of the proximal phalanx in the retrocondylar recess

beneath the oblique pulley, and gives branches to the

flexor pollicis longus through the vincula brevia, the

palmar plate, the interphalangeal joint, and the flexor

sheath. The pulp arch is in the recess just proximal to the

tuft of the distal phalanx, and gives multiple branches

to the pulp and nail bed.

FIGURE 10.28. Index radiopalmar

digital artery. Three main origins for

this artery were seen identified in the

Earley study (24): (A) a branch of the

main stem or superficial ulnar artery

in 5 of 20 hands, (B) a branch of the

second palmar metacarpal artery in 5

of 20 hands, and (C) a branch of the

superficial palmar branch of the

A–C radial artery in 5 of 20 hands.

artery in the snuff-box and followed a course along the EPB

and abductor pollicis longus tendons, traveling toward the

dorsal skin at the thumb MCP joint.

Based on his study and a review of the related literature,

Earley made the observations that are summarized as follows:

1. Tandler (33) noted that the SPBR branch was as large as

the superficial or main stem of the ulnar artery in the

palm in over one-third of hands, and that in these hands

it often supplied the thumb ulnopalmar and index

radiopalmar digital arteries through a first web common

digital artery.

2. Tandler (33) stated that the first PMA was “certainly not

the main blood vessel of the thumb” and thus did not

deserve the name “arteria princeps pollicis.” Earley

noted that the ulnopalmar artery (the major artery to the

thumb) is derived from the first PMA in only half of the

hands he dissected (24).

3. Confusion has existed as to whether the origin of the

artery to the index finger is superficial or deep, but both

Weathersby (41) and Coleman and Anson (25) realized

that this depended on the relative dominance of either

arterial system. Weathersby, in a study of 256 palmar

arches, found that the main index finger supply comes

from the deep arch in 45%, the superficial arch in 13%,

and both in 42%, and believed that the name arteria

volaris indicis should be abandoned in favor of second

PMA or third common digital artery (41). Earley found

that the second PMA, which supplied the whole index

and middle finger radiopalmar digital artery, occurred in

5 of 20 hands (24).

Surgical Applications Based on the Earley Study

1. Interruption of the ulnar artery at the wrist may result in

loss of blood flow in the second through fourth interdigital cleft vessels and possibly lead to ischemia in the

fingers. Thumb viability would not be affected because

both sides of the thumb never are supplied only by the

superficial palmar artery.

2. Interruption of the radial artery at the wrist could be a

different matter, especially in those hands with a large

contribution from the SPBR (30% of hands in Earley’s

study), because the common digital as well as palmar

metacarpal arterial supply would be lost. However,

ischemia leading to necrosis might not occur if sufficient

interconnections were present from other arterial systems.

3. Landmarks for the arteries of the thumb are the FPL at

the metacarpal level, the sesamoid bones, and the

oblique pulley of the flexor sheath. The distal part of the

oblique pulley marks the level of the digitopalmar arch.

When looking for the ulnopalmar thumb digital artery,

it is helpful to remember the “preadductor” or “postadductor” course of the artery and the possibility of its origin from the dorsal vessels. In 90% of cases, the ulnopalmar artery is the largest of the two thumb arteries and

should be considered as the first choice for anastomosis

in replantation. If the ulnopalmar artery is not suitable

for anastomosis, the A1 pulley area and the ulnar side of

the radial sesamoid should be examined to locate the

radiopalmar digital artery. By this means, the deep variety (seen in 50%) can be identified before it courses

deep to the flexor sheath.

Author’s Comments

There is no standard pattern of arterial supply to the thumb

or index finger. Although the use of fresh cadaver specimens

and injection techniques may add to our understanding,

the differences noted in the various studies are not easily

explained. The comments of Ames et al. (23) regarding the

factors that may limit an anatomic study are repeated here

and include (a) the quality of the specimen and injection,

and (b) the examiner’s ability to perceive order amidst

diversity. Finally, in reference to the arterial circulation to

the thumb, the term princeps pollicis probably is a misnomer

and should be abandoned.

Nerves of the Hand

Cutaneous Innervation of the Palm

Martin et al. studied the innervation of the proximal palm

in 25 fresh cadaver hands to determine the most appropriate location for the incision for an open carpal tunnel

release (42). A carpal tunnel release incision was made in

each of the 25 hands curving in line with the axis of the ring

finger. The location of the nerve relative to the incision was

noted, and all nerves cut or passing within 2 mm of the

incision were considered to be at risk for injury.

Four nerves were identified, one from the median [the

palmar cutaneous branch of the median nerve (PCBMN)]

and three from the ulnar [the palmar cutaneous branch of

the ulnar nerve (PCBUN), the nerve of Henle, and transverse palmar branches from the ulnar nerve in Guyon’s

canal] (Fig. 10.29).

Palmar Cutaneous Branch of the Median Nerve

This nerve was present in all specimens and originated from

the radial side of the median nerve an average of 5.9 cm

(range, 4.1 to 7.8 cm) proximal to the wrist flexion crease.

In two hands, two distinct nerves were identified. The

PCBMN coursed distally in the interval between the palmaris longus and the FCR tendons. In each specimen, the

nerve pierced the distal antebrachial fascia and palmar fascia in its own tunnel, often weaving through the fibers of

the palmaris longus. In all cases the nerve became subcutaneous radial to the palmar incision. In one case, a large

branch of the nerve crossed the incision and would likely

568 Regional Anatomy

have been transected during an open carpal tunnel release.

In another two specimens, the terminal ulnar fibers of the

PCBMN were identified at the incision margin. In each of

the three specimens in which the PCBMN was considered

at risk, ulnar palmar cutaneous nerves also were at risk.

Summary of PCBMN: Incidence, 25 of 25; at risk, 3 of 25.

Ulnar Nerve Branches

Palmar Cutaneous Branch of the Ulnar Nerve. This

nerve was identified in 4 of 25 specimens and originated an

average of 4.6 cm proximal to the pisiform (range, 3 to 7.8

cm). In each case the nerve traveled superficial to the palmar carpal ligament. In one case, the PCBUN traveled

directly superficial to the palmaris brevis but gave no motor

fibers to the muscle. Each of these four nerves became subcutaneous ulnar to the palmar incision, and two of the four

were transected by the incision toward their radial extent.

Summary of PCBUN: Incidence, 4 of 25; at risk, 2 of 4.

Nerve of Henle. This nerve, the nervi vasorum of the ulnar

artery, gave innervation to the forearm or palm in 14 of 25

hands, in addition to providing sympathetic innervation to

the artery. Eleven nerves of Henle providing innervation to

the palm were noted in 10 of 25 specimens, with 1 artery

having two distinct bundles. These nerves originated an

average of 16.3 cm (range, 9 to 27 cm) proximal to the pisiform. In most, the nerve originated at a point in the proximal forearm where the ulnar nerve passes through the FCU

to lie alongside the ulnar artery. In one case, the nerve

received a substantial contribution from the median nerve

in the proximal forearm. The cutaneous component of

these nerves diverged from the ulnar artery near the proximal wrist crease, coursing between the tendons of the FCU

and FDS to the ring finger. Proximal to the palm, the

nerves pierced the distal antebrachial fascia, becoming subcutaneous at the distal wrist flexion crease. In six specimens,

one or more branches of the cutaneous portion of the nerve

of Henle was either transected or at risk from the incision.

Summary of nerve of Henle: Incidence, 10 of 25; at risk,

6 of 10.

Transverse Palmar Cutaneous Branches of the Ulnar

Nerve. Multiple cutaneous nerves to the palm were noted

from the ulnar nerve, the ulnar motor branch to the

hypothenar muscles, and the common digital ulnar sensory

nerve as they coursed through Guyon’s canal. At least 1 such

10.1 Palmar Hand 569

FIGURE 10.29. Cutaneous innervation of

the palm as it relates to open carpal tunnel

release [based on a study of 25 hands by

Martin et al. (42)]. Four nerves were identified to be at risk (all nerves cut or passing

within 2 mm of the incision): the palmar

cutaneous branch of the median nerve; the

palmar cutaneous branch of the ulnar

nerve; the nerve of Henle; and transverse

palmar branches from the ulnar nerve in

Guyon’s canal. See text for details of nerve

incidence and risk. Based on this study, the

authors concluded that there is no internervous plane in this region of the palm.

nerve was identified in 24 specimens (average, 1.8; range, 1

to 5). The origin of these nerves averaged 3 mm distal

(range, 1.8 cm proximal to 1.7 cm distal) to the center of

the pisiform and was variable with respect to the ulnar

nerve branch of origin. In two specimens, these nerves traveled with the ulnar artery for less than 1 cm before becoming cutaneous. Many of these nerves exited perpendicularly

from the longitudinal direction of the ulnar nerve, thus

prompting a description of them as transverse. These nerves

pierced the palmar carpal ligament to innervate the skin

and subcutaneous tissue of the hypothenar eminence and

midpalm, usually distal to that area innervated by either the

nerve of Henle or the PCBUN. The radial extent of these

nerves was very variable, but they routinely extended farther

radial than the site of the carpal tunnel release incision in

the axis of the ring finger. In 11 specimens, at least one of

these transverse palmar cutaneous branches was either transected or at risk by the palmar incision.

Summary of transverse PCBUN: Incidence: 24 of 25; at

risk, 11 of 24.

Clinical Significance

Based on this study, there is no internervous plane in this

region of the palm. Injury to these nerves may explain the

lower rate of painful incisions after endoscopic carpal tunnel release compared with open release.

Palmar Cutaneous Branch of the Median Nerve. Watchmaker et al., in a study of 25 cadaver hands, noted the risks

of injury to the PCBMN during carpal tunnel surgery (43).

They identified what they considered to be a more reliable

landmark for placement of the carpal tunnel release incision

that was not based on the variable and ambiguous axis of

the ring finger or the thenar crease. They noted that the

PCBMN arose on average 41 mm proximal to the distal

wrist flexion crease (range, 27 to 63 mm), and at that level

was 2 mm radial to the thenar crease (range, 6 mm radial to

6 mm ulnar). The PCBMN could be traced 3.5 to 4 cm distal to the distal wrist crease. Further observations by the

authors revealed that the thenar crease did not extend proximally to cross the wrist flexion crease but rather began an

average of 18 mm distal to wrist crease, and that the thenar

crease may turn radially at this point and bifurcate. The

PCBMN was noted to underlie or cross beneath the thenar

crease, making this crease a poor choice for a carpal tunnel

release incision. The authors’ incision of choice was identified as the depression between the thenar and hypothenar

eminences. They noted that the PCBMN courses an average of 4 to 4.5 mm radial to this depression. In no specimen

was the PCBMN ulnar to the depression. In two specimens,

a branch of the PCBMN passed beneath the depression;

thus, an incision placed several millimeters (the authors

advised 5 mm) ulnar to the depression was noted to provide

a safe territory for the incision.

Author’s Comment. The observation of Martin et al. (42)

that there is no internervous plane in this region of the

palm bears repeating. Based on the two studies just

reviewed, it seems apparent that most incisions in this zone

may affect at least one sensory cutaneous branch derived

from median or ulnar sources because the demonstrated

regions of innervation overlap.

Median Nerve

Classic Description of the Course and Branching of

the Median Nerve

The median nerve, as a single large nerve, enters the hand

beneath the TCL accompanied by nine flexor tendons (Fig.

10.30). Near the distal margin of the TCL, the median nerve

usually divides into three common palmar digital components, although it often may divide first into a radial and ulnar

trunk (1). The motor branch most often arises from the radial

side of the most radial component of the nerve. The classic

description of the division of this most radial trunk is (a) a trifurcation of the radial trunk into proper digital nerves (PDNs)

to the radial and ulnar sides of the thumb and the radial side

of the index finger, or (b) a common nerve branch to the

thumb that divides into proper radial and ulnar digital nerves

to the thumb and a PDN branch to the radial side of the

index finger. The remaining central and ulnar common digital branches course distally and divide into the PDNs to the

ulnar side of the index finger, both sides of the middle finger,

and the ulnar side of the ring finger. The motor branch to the

index finger lumbrical arises from the proper sensory branch

to the index finger, and the branch to the middle finger lumbrical from the common digital nerve to the index–long finger web space.

This classic description is appropriately compared with a

study by Jolley et al., who noted the following patterns of

branching in a study of 79 embalmed cadaver hands (44).

Their three patterns of branching are presented in order of

frequency.

Type A. This type consists of a PDN to the radial side of

the thumb and a common digital nerve of variable length to

the first web space that divides into a branch to the ulnar

side of the thumb and radial side of the index finger. This

was the most common configuration, seen in 54 of 79

hands (69%).

Type B. This type is a trifurcation pattern with PDNs arising from the median nerve to course to the radial and ulnar

aspects of the thumb and the radial side of the index finger,

seen in 20 of 79 hands (25%).

Type C. A common digital nerve to the thumb divides into

proper radial and ulnar nerves and a proper radial digital

nerve to the index finger (see Fig. 10.30B). This was the

least common pattern, seen in 5 of 79 hands (6%).

570 Regional Anatomy

10.1 Palmar Hand 571

FIGURE 10.30. A: Median and ulnar nerves and their most common pattern of branching. The

most common pattern of median nerve branching to the thumb and radial side of the index finger, as described by Jolley et al. (44), is at variance with the classic descriptions of branching. See

text for details of nerve branching. B: Patterns of median nerve sensory branching to the thumb

and index finger, after Jolley et al. (44).

(continued on next page)

A

B

Clinical Significance

The most common pattern of median nerve branching to

the thumb and radial side of the index finger as described

by Jolley et al. is at variance with the classic descriptions of

branching. Surgeons should be aware that the most common median nerve branching in the first web space is that

of a PDN branch to the radial side of the thumb and a common digital nerve that divides to innervate the ulnar side of

the thumb and the radial side of the index finger.

Digital Nerves

In general, the PDNs course distally in intervals adjacent to

the lumbrical muscles and flexor tendon sheaths (Fig. 10.31;

see Fig. 10.30). They are deep to the superficial palmar arterial arch and its arterial branches and remain deep to these

vessels until they (the nerves) exit from beneath the transverse

fibers of the palmar fascia into a fat pad at the distal aspect of

the palm. The PDNs enter the digits beneath the natatory

ligament, palmar to the transverse metacarpal ligament, and

adjacent to the longitudinal fibers of the palmar fascia; in the

digits, the nerves are palmar to the arteries. In the fingers, the

PDN lies adjacent to the flexor sheath and level with the palmar aspect of the phalanges. Each PDN gives off several

branches to the sides and palmar aspect of the finger, as well

as branches to the adjacent joints. These nerves supply the

flexor tendon sheaths, the digital arteries, and sweat glands

(1). In a study of 30 fresh cadaver hands, Bas and Kleinert

found that the dorsal branch of the PDN that supplied the

skin over the dorsum of the middle and distal phalanges

divided from the PDN more proximally than previously

described. In 62% of the PDNs for the index, long, ring, and

small fingers, the dorsal branch arose from the PDN in the

area of the A1 pulley or proximal to it (45). In the thumb, the

dorsal sensory branch, when present (11 of 30 thumbs), arose

distal to the A1 pulley (45).

Joint Innervation

In a study of 12 fresh cadaver hands using microdissection

and selective silver staining, Chen et al. found that the PIP

572 Regional Anatomy

FIGURE 10.30. (continued) C: Fresh cadaver dissection showing

an “accessory thenar nerve” (ATN) distal to the transligamentous

recurrent motor branch (bracketed by green markers) of the

median nerve. In Mumford and colleagues’ (48) study of the

recurrent motor branch, 15 of 20 specimens (75%), demonstrated an ATN that innervated the flexor pollicis brevis and

arose from either the first common digital nerve (25%) or the

radial proper digital nerve to the thumb (50%).

FIGURE 10.31. Relationship of the digital nerves and arteries to

each other and to the natatory ligament and the palmar fascia.

C

joints were innervated by two palmar articular nerves, one

proximal and one distal, that originated from the PDNs

and had a mean diameter of 0.21 to 0.53 mm (46). These

branches were found to innervate the palmar part of the

joint capsule, the head of the proximal phalanx, the tendon

sheath, and the lateral aspect of the capsule. The PIP joints

also had dorsal proximal articular nerves that originated

from the superficial branches of the radial nerve in the

index and long fingers and the ulnar nerve in the ring and

small fingers. Each MCP joint of the index through small

fingers was supplied by one palmar articular nerve (mean

diameter, 0.41 to 0.59 mm) that originated from the deep

branch of the ulnar nerve. Proximal to the A1 pulley, this

palmar articular nerve branches into the palmar and lateral

aspect of the MCP joint capsule, the metacarpal head, and

the tendon sheath. Two dorsal articular nerves (mean diameter, 0.11 to 0.24 mm) were found that originated from the

radial and ulnar sides of the dorsal digital nerve and

branched into the dorsal capsule, sagittal band, and dorsal

aspect of the metacarpal head. The thumb MCP joint had

two dorsal articular nerves (mean diameter, 0.18 to 0.24

mm) and two palmar nerves (mean diameter, 0.29 to 0.31

mm). The thumb palmar articular nerve originated from

each side of the palmar digital nerve rather than from the

ulnar nerve, as in the fingers.

Index Finger Digital Nerves

In the most common pattern of index finger innervation

(74%), the nerves pass through the palm deep to the digital artery. The nerve to the ulnar side passes beneath the

natatory ligament and palmar to the transverse metacarpal

ligament. Both nerves in the index finger are palmar to the

digital arteries, in contrast to their deep position in the

palm. At the DIP crease, the nerves divide into three or four

branches supplying the pulp and nail bed. At or proximal to

the A1 pulley, the dorsal branch arises either deep or superficial (approximately equally often) to the digital artery. The

dorsal branch of the PDN usually perforates Cleland’s ligament and often connects with the terminal branches of the

radial nerve, called the dorsal sensory nerve, to supply the

skin over the dorsal aspect of the middle and distal phalanges (45). The depth of the palmar digital nerves in the

index finger was approximately 3 mm, and was even more

superficial at the digital creases (47).

Thumb Digital Nerves

These nerves pass distally on the radial and ulnar side of the

thumb palmar to the digital artery, and at the level of the

interphalangeal crease divide into three or four branches to

supply the pulp and nail bed (see Fig. 10.30). Wallace and

Coupland noted that no dorsal branches are given off;

although in approximately one-third of cases a short branch

to the skin over the radial side of the MCP joint arises from

the radial palmar digital nerve (47). These nerves supply

only the palmar aspect of the thumb, thumb pulp, and nail

bed. No crossovers or interconnections of the nerve were

noted (47). These findings are compared with those of Bas

and Kleinert, who noted both radial and ulnar dorsal

branches from the thumb PDN in 11 of 30 hands (45). The

digital nerve to the radial side of the thumb passes over the

FPL near the A1 pulley and is at risk during a trigger thumb

release.

Recurrent Motor Branch (Thenar Nerve)

Classic Configuration

The recurrent motor branch arises from the ulnopalmar

aspect of the radial division of the median nerve, usually

just distal to the TCL; it then curves proximally and palmarward to lie on the superficial portion of the FPB (see

Fig. 10.30A and B). It continues in this fashion until it

reaches the interval between the APB and the FPB, at which

junction it enters the interval between these two muscles

and continues through the APB to reach the underlying and

more radial OP.

The classic description of this branch is a single branch

with terminal branches, one each to the FPB, APB, and OP.

In a study of 20 cadavers, Mumford et al. found that 9 of

20 specimens (45%) demonstrated this classic pattern (48).

Variations in Origin of the Motor Nerve

In Mumford and colleagues’ study, the thenar nerve originated from the median nerve at or beyond the distal edge of

the TCL in 16 of 20 specimens (80%), and in 4 specimens

(20%) it originated a few millimeters proximal to the distal

edge of the TCL.

Spatially, the thenar nerve arose from the ulnopalmar

aspect of the radial division of the median nerve in 16 specimens (80%), and in 4 specimens (20%) from the radiopalmar aspect of the radial division (48).

Mumford and colleagues’ description is appropriately

compared with the studies of Poisel, Lanz, and Tountas et

al. (49–51) in reference to the motor branch as well as other

variations of the median nerve in this region.

Variations in Relationship of the Motor Nerve to the

Transverse Carpal Ligament

Poisel, in 1974, studied the relationship of the thenar nerve

to the TCL in 100 cadaver hands, and the following frequencies were noted: 46% extraligamentous, 31% subligamentous, and 23% transligamentous (49). Less common

variations, noted by others, in the subligamentous category

include the thenar nerve leaving the median nerve on its

ulnar aspect (52), and bending of the thenar branch around

the distal edge of the TCL, where it then courses on top of

the TCL before entering the ligament (53).

Lanz, in 1977, published his findings in 246 hands, noting the variations in the course of the motor branch, the

10.1 Palmar Hand 573

accessory branches at the proximal and distal ends of the

carpal canal, and high division of the median nerve (50).

Tountas et al. (51) studied the same categories as to frequency and compared their findings with those of Poisel

and Lanz (49,50). The study by Tountas et al. was a combined retrospective and prospective study. The operative

reports of 535 carpal tunnel releases were reviewed (retrospective study), and 286 cases were evaluated prospectively.

In addition, 92 cadaver hands were dissected. The results of

the Tountas et al. study are noted in Table 10.5. This study

was at significant variance with the Poisel findings.

Author’s Comments and Conclusions. A significant difference was noted by Tountas et al. between their study and

that of Poisel when comparing the course of the motor

branch and its relationship to the TCL (49,51). Whereas

Poisel found that the motor branch of the median nerve was

extraligamentous (probably the normal arrangement) in

46% of his cases, Tountas et al. found an incidence of 82%

in their dissections and 96% in their clinical cases. Similarly, the incidence of transligamentous distribution of the

motor branch was 31% in Poisel’s series, compared with an

incidence of 9% in the dissections and slightly over 1% in

the clinical cases for Tountas et al. My surgical experience

more closely resembles the findings of Tountas et al.

Although differences in the frequency of anatomic variations have been noted in this area, it still is obvious that significant variation in the course and branching of the

median nerve is present at the wrist and in the hand. It is

important to be aware of these variations and to note that

the most likely zone of safety when approaching the median

nerve in the carpal tunnel is to the ulnar side, although

branches from the ulnar side may arise proximally, in the

carpal tunnel, or distal to the tunnel.

Variations in Branching at the Distal Aspect of the

Carpal Tunnel

Variations identified by Mumford et al. included one main

trunk with two branches (one branch to the APB and one

to the OP, but no branch to the FPB) in six specimens

(30%) (48). The remaining five specimens (25%) demonstrated four other patterns with either two, three, or four

branches off the main trunk. In addition, in 15 specimens

(75%), an “accessory thenar nerve”, which innervated the

FPB, arose from either the first common digital nerve

(25%) or the radial PDN to the thumb (50%). Lanz, based

on his study of 246 hands, commented that a true double

motor branch was a rare occurrence (50). He noted that the

thin branches sometimes seen arising from the palmar or

even the ulnar aspect of the nerve were sensory fibers based

on the results of intraoperative nerve stimulation and exact

dissection following the branches to the skin. He recommended preserving these branches to avoid the possible

occurrence of neuromata (50).

The findings of Tountas et al. (51) regarding variations

in branching are given in Table 10.6.

Variations in Branching Proximal to the Carpal Tunnel.

Lanz, in his series of 246 carpal tunnel operations, identified 4 accessory nerves that originated proximal to the TCL

(50). The first nerve noted perforated the TCL and joined

the recurrent motor branch distally. The second accessory

branch (nonmotor) proximal to the TCL left the median

nerve at its ulnar aspect, perforated the TCL in its proximal

third, and joined the common digital nerve to the thumb

and radial side of the index finger. In the third and fourth

cases, an accessory motor branch arose proximal to the TCL

and coursed through the proximal aspect of the TCL to

enter the thenar muscles. This motor nerve branch was in

addition to the motor nerve arising from the distal aspect of

the carpal canal. Two cases of a similar configuration were

reported by Linburg and Albright (54). The findings of

Tountas et al. (51) regarding variations in branching proximal to the carpal tunnel are given in Table 10.7.

574 Regional Anatomy

TABLE 10.5. VARIATIONS IN RELATIONSHIP OF THE

MEDIAN MOTOR NERVE TO THE TRANSVERSE

CARPAL LIGAMENT

Findings/Frequency

Extra- Sub- TransStudy ligamentous ligamentous ligamentous

Retrospective 522 9 4

Prospective 272 8 6

Dissections 75 9 8

TABLE 10.6. VARIATIONS IN BRANCHING OF THE

MEDIAN MOTOR NERVE AT THE DISTAL ASPECT

OF THE CARPAL TUNNEL

Study Findings/Frequency

Retrospective One double motor branch

Prospective Two double motor branches

Dissections Two double motor branches (one motor

branch arose distal to the transverse carpal

ligament, passed proximally, anterior to the

ligament, and entered the thenar muscles

proximal to the carpal tunnel)

TABLE 10.7. VARIATIONS IN BRANCHING

PROXIMAL TO THE CARPAL TUNNEL

Study Findings/Frequency

Retrospective Two

Prospective Six

Dissections None

High Division of the Median Nerve

Lanz, in 246 dissections, noted 5 high divisions of the

median nerve, which were associated with a median artery

that was of variable size (50). Both parts of the nerve were

of the same diameter. Similar findings were reported by

Eiken et al. (55). Kessler described a high division of the

median nerve without an associated median artery in which

the ulnar part of the nerve was larger than the radial (56).

Lanz noted that in two of his cases of high division of the

median nerve, the caliber relationship was just the opposite

(50). These findings are appropriately compared with those

of the Tountas et al. study; the findings of Tountas et al.

(51) regarding the incidence of high division of the median

nerve are given in Table 10.8.

Ulnar Nerve

Classic Course and Configuration

The ulnar nerve, accompanied by the ulnar artery on its

radial side, enters the hand on the radial side of the pisiform

bone through Guyon’s canal (Fig. 10.32; see Fig. 10.20). At

this level, the ulnar nerve divides into motor and one or two

sensory branches (see discussion to follow).

Ulnar Motor Branches

The motor component of the nerve at the level of the pisiform is ulnar and dorsal. The motor branch gives off one to

three (usually two) branches to the hypothenar muscles

before it enters the depths of the palm. Its course into the

palm has been variously described as passing between the

origin of the FDM and ODM or beneath the proximal origin of the FDM (1,28). It then courses around the ulnar

and distal aspect of the base of the hook process of the

hamate. The proximal edge of the FDM often (14 of 23

cases) demonstrates a fibrous arcade where the motor

branch may become entrapped (28). It then traverses the

hand to innervate the ring and small finger lumbricals, the

palmar and dorsal interossei, the adductor pollicis, and the

deep head of the FPB.

Ulnar Sensory Branches

After division into a sensory trunk and motor branch in

Guyon’s canal, the sensory component divides into the sensory branch to the ulnar side of the small finger (the proper

palmar digital) and the common sensory nerve, which

courses to the fourth web and divides there to become the

PDN of the radial side of the small finger and the ulnar side

of the ring finger. The motor branch to the palmaris brevis

usually arises from the sensory branch to the small finger

(27). The communicating branch from the common sensory (ulnar) courses distally to join the common median

sensory to the third web space.

Anatomy of Guyon’s Canal

Guyon’s canal, or the ulnar tunnel, is the space that the

ulnar nerve and artery traverse to gain entrance to the hand

from the forearm. Guyon’s canal begins at the proximal

edge of the palmar carpal ligament and ends at or beyond

the fibrous arch of the hypothenar muscles (formed mainly

by the FDM). Beginning from proximal to distal, the roof

of the canal is formed by the palmar carpal ligament, portions of the palmar aponeurosis, and the palmaris brevis

muscle. The floor is formed by the TCL, the pisohamate

and pisometacarpal ligaments, and the FDM. The ulnar

wall is composed of the FCU, the pisiform, and the ADM.

The radial wall is formed by the tendons of the extrinsic

flexors, the TCL, and the hook process of the hamate (27,

28,57,58). According to Lindsey and Watamull, the average

length of Guyon’s canal is 27 mm (range, 20 to 34 mm),

and according to Kuschner et al., it is approximately 40 mm

in length (27,57). The ulnar nerve and artery branches in

this region are covered by the palmaris brevis muscle and

surrounded by a thick fat pad. Konig et al. observed that the

distal aspect of Guyon’s canal has both a superficial and a

deep exit (28). The superficial exit conducts the superficial

sensory nerve and main trunk of the ulnar artery over the

ADM and FDM distally, whereas the deep or motor branch

is conducted through a deep exit beneath the fibrous proximal edge of the FDM and thus into the mid-palmar aspect

of the hand (28).

Gross and Gelberman divided Guyon’s canal into three

zones (58). Zone 1 was from the proximal edge of the proximal commissural ligament (PCL) to the bifurcation of the

ulnar nerve. Zones 2 and 3 were parallel zones that began at

the bifurcation of the nerve and, according to these authors,

ended at the region just beyond the fibrous tissue arch of

the hypothenar muscles. Zone 2 contained the motor

branch of the ulnar nerve, and zone 3 contained the sensory

branch of the nerve. Zones 2 and 3 are comparable with the

deep and superficial exits, respectively, of Konig et al.

Author’s Comment. Zones 2 and 3 are not divided by an

anatomic structure but rather are arbitrary divisions that

have useful clinical applications (see discussion to follow).

Also, at this distal aspect of Guyon’s canal, the motor and

sensory components of the ulnar nerve begin to separate in

both the radioulnar and the dorsopalmar direction. The

sensory branch exits the canal from beneath the distal edge

10.1 Palmar Hand 575

TABLE 10.8. INCIDENCE OF HIGH DIVISION OF THE

MEDIAN NERVE

Study Findings/Frequency

Retrospective Two (median artery with bifid nerve)

Prospective Six (five median artery with bifid nerve,

one bifid nerve)

Dissections Two (one bifid nerve with median artery

and one bifid nerve that had a branch

coming off the radial division)

576 Regional Anatomy

FIGURE 10.32. The ulnar nerve in Guyon’s canal. A: Relationships of the ulnar nerve and artery

in Guyon’s canal. According to Lindsey and Watamull (27), the ulnar nerve may divide into motor

and sensory components proximal to, at, or in Guyon’s canal. The most common configuration

(approximately two-thirds in a study of 31 hands) is division into a main sensory and motor

branch in Guyon’s canal an average 8.6 mm from the proximal edge of the pisiform (range, 0 to

15 mm). See text for details.

A

of the palmaris brevis muscle and is palmar and ulnar to the

motor branch. Konig et al. called this exit the superficial distal hiatus (28). Thus, as far as the sensory branch is concerned, Guyon’s canal ends at the distal edge of the palmaris

brevis muscle. Although the motor component also exits

from beneath the distal edge of the palmaris brevis muscle,

it soon enters either the interval between the FDM and the

adjacent ADM or courses beneath the proximal origin of

the FDM. This exit, termed the deep distal hiatus by Konig

et al., often (14 of 23 cases in Konig et al.) is bounded by a

fibrous tissue arcade (28). Although there is some described

variance in the exact exit route of the motor nerve, the

point of clinical relevance is that the motor branch at this

level may be subject to neuropathic influences. The fibrous

tissue arcade may play a role in compression neuropathy.

The motor branch then turns and descends dorsally around

the ulnar and distal aspect of the hook process of the

hamate on its way to the deeper aspects of the palm.

Because the motor branch is subject to neuropathic influences at this level, this region might be considered to be

part of Guyon’s canal. This concept matches to some extent

the anatomic descriptions and clinical implications of this

region proposed by Gross and Gelberman, Kuschner et al.,

and Konig et al. (28,57,58).

Clinical Significance of the Three Zones of Guyon’s

Canal. Kuschner et al. found these zones to be useful for

the localization and correct prediction of the cause of ulnar

neuropathy in Guyon’s canal (57). Based on their review of

ulnar compression cases, they noted the causes summarized

in Table 10.9.

Kuschner et al. concluded that their division of Guyon’s

canal into zones, along with a careful history and examination, including sensory and motor tests, Allen’s test, palpation for subtle masses, and diagnostic studies such as radiographs of the carpal tunnel, would result in a more

accurate prediction of the cause of the ulnar deficit.

By determining the neurologic deficits (motor, sensory,

or both), one may discover the zone in which the lesion

may be found and form an appropriate differential diagnosis based on the history (57).

Patterns of Branching of Ulnar Nerve at the Wrist

Ulnar Nerve Branching. Two patterns of division of the

ulnar nerve have been identified in a study of 31 cadaver

hands, types A and B (27) (Fig. 10.33).

Type A (80.6%). The ulnar nerve divided into a main sensory

trunk and motor branch. In 20 instances, the nerve divided in

Guyon’s canal (average, 8.6 mm from the proximal edge of the

pisiform; range, 0 to 15 mm). In the remaining five, the division was proximal to the canal (average, 12.6 mm proximal to

the proximal edge of the pisiform; range, 7 to 25 mm).

Type B (19.4%). In this pattern, the ulnar nerve trifurcated

into two common digital sensory branches and a motor

branch. The trifurcation occurred in Guyon’s canal in all

specimens (average, 10 mm from the proximal edge of the

pisiform; range, 3 to 20 mm).

Similar findings of ulnar nerve division were noted by

Bonnel and Vila, who found that 39 of the 50 specimens

demonstrated the usual division of the ulnar nerve into 2

branches, 1 superficial (sensory) and 1 deep (motor) (59).

In 11 cases, the nerve divided into 3 branches consisting of

a deep motor branch, the proper digital branch to the ulnar

side of the small finger, and a common palmar digital nerve

of the fourth interosseous space.

10.1 Palmar Hand 577

FIGURE 10.32. (continued) B: Fresh cadaver dissection of

Guyon’s canal: The proximal blue marker is beneath the motor

component of the ulnar nerve and is just proximal to the pisohamate ligament; the green marker is beneath the motor

branch; the red marker is beneath the arterial branch to the

hypothenar muscles; and the distal blue marker is beneath a

motor branch to the hypothenar muscles. Note that the sensory

component of the nerve has been moved radially to expose the

motor branch. The sensory component divides into the proper

digital nerve to the ulnar side of the small finger and the common digital nerve to the small/ring web space.

B

578 Regional Anatomy

TABLE 10.9. AREAS OF ULNAR NERVE COMPRESSION IN GUYON’S CANAL AND THEIR CAUSESa

Areas of Compression

Deficit Zone 1 Zone 2 Zone 3 Causes (%)

Motor and sensory 42 Ganglions (45)

Fractures (36)

Anomalous muscles (7)

Motor alone 1 42 Ganglions (60)

Fractures (12)

Thickened pisohamate ligament (7)

Sensory alone 7 10 Thrombosis (30)

Synovitis (24)

Anomalous muscles (12)

aThese causes represent the most frequent causes of ulnar nerve compression and do not add up to 100%. Those patients with combined

motor and sensory loss without a history of trauma had a ganglion as the cause of the ulnar deficit 70% of the time. Isolated motor deficits

occurred most frequently in zone 2 and were due to a ganglion 60% of the time. Isolated sensory deficits occurred most commonly from

compression in zone 3, but also may occur in zone 1; thrombosis of the ulnar artery was the most frequent cause.

FIGURE 10.33. Patterns of branching of ulnar nerve at the

wrist, after Lindsey and Watamull (27). I: Two patterns of

division of the ulnar nerve have been identified in a study of

31 cadaver hands. Type A (25 of 31 hands): The ulnar nerve

divided into a main sensory (S) trunk and motor (M) branch.

In 20 instances, the nerve divided in Guyon’s canal (average,

8.6 mm from the proximal edge of the pisiform; range, 0 to

15 mm); in the remaining 5, the division was proximal to the

canal (average, 12.6 mm proximal to the proximal edge of

the pisiform; range, 7 to 25 mm). Type B (6 of 31 specimens):

In this pattern, the ulnar nerve trifurcated into two common

digital sensory branches and a motor branch. The trifurcation occurred in Guyon’s canal in all specimens (average, 10

mm from the proximal edge of the pisiform; range, 3 to 20

mm). II: Hypothenar muscle branches. Pattern type 1 (10 of

31 cases): This pattern was represented by a single nerve

branch that innervated the flexor digiti minimi and opponens digiti minimi through the abductor digiti minimi. Pattern type 1 usually (80%) branched in Guyon’s canal, and its

origin from the main motor branch was 16 mm (average;

range, 11 to 25 mm) distal to the proximal edge of the pisiform. However, in one case each it was noted to branch distal and proximal to the canal a distance of 30 and 25 mm,

respectively. Pattern type 2 (14 of 31 cases): This pattern was

represented by two branches from the main motor branch.

These branches originated in Guyon’s canal 68% of the time

(average, 18 mm distal to the proximal edge of the pisiform;

range, 0 to 32 mm). In 32%, the two branches arose 30 mm

distal to the canal (range, 27 to 46 mm). Pattern type 3 (7 of

31 cases): This pattern was represented by three or more

branches. All branches arose in the canal in 76% (average,

20 mm distal to the proximal edge of the pisiform; range, 3

to 30 mm). In 24%, the branches arose distal to the canal

(average, 31 mm; range, 30 to 40 mm). III: Innervation of

palmaris brevis (PB). In the type A division (one motor and

one sensory branch), the PB is innervated by a branch that

originates from the ulnar division of the sensory branch, and

in the type B division (one motor and two sensory branches),

the PB branch originates from the most ulnar of the two

sensory branches.

I

II

III

Sympathetic Nerve Branching. Lindsey and Watamull

found that a sympathetic branch originated from the sensory trunk or from the common digital nerve to the fourth

interosseous space and communicated with the superficial

palmar arch in 12 of 31 specimens (27). This branch, when

present, arose distal to Guyon’s canal in 11 cases, an average

of 34 mm from the proximal edge of the pisiform. In the

remaining case, it arose in Guyon’s canal 10 mm from the

proximal edge of the pisiform.

Innervation Patterns of the Hypothenar Muscles. Pattern

Type 1 (10 of 31 Cases). This pattern was represented by a

single nerve branch that innervated the FDM and ODM

through the ADM. This single branch arborized either before

or on contact with the abductor. In contrast, the flexor and

opponens muscles had identifiable separate nerve supplies in

pattern types 2 and 3, where two or more branches were present. Pattern type 1 usually (80%) branched in Guyon’s

canal, and its origin from the main motor branch was an

average of 16 mm (range, 11 to 25 mm) distal to the proximal edge of the pisiform. However, in one case each it was

noted to branch distal and proximal to the canal by a distance

of 30 mm and 25 mm, respectively.

Pattern Type 2 (14 of 31 Cases). This pattern was represented by two branches from the main motor branch. These

branches originated in Guyon’s canal 68% of the time, an

average of 18 mm (range, 0 to 32 mm) distal to the proximal edge of the pisiform. In 32%, the two branches arose

an average of 30 mm distal to the canal (range, 27 to 46

mm).

Pattern Type 3 (7 of 31 Cases). This pattern was represented

by three or more branches. All branches arose in the canal

in 76%, an average of 20 mm (range, 3 to 30 mm) distal to

the proximal edge of the pisiform. In 24%, the branches

arose distal to the canal by an average of 31 mm (range, 30

to 40 mm).

Clinical Significance of the Variations in the Neurovascular

Pedicle to the Hypothenar Muscles. Preservation of the innervation and circulation to the ADM is critical to the success

of the opposition transfer using this muscle described by

Huber (60). In Lindsey and Watamull’s study of the nervous and vascular anatomy of Guyon’s canal in 31 hands,

73% of the hypothenar nerve branches were found in

Guyon’s canal; 25% occurred distal to the canal; and only 1

branch was found proximal to the canal. Ten of the 31

hands demonstrated a single nerve branch to the

hypothenar muscles, and thus it is theoretically possible to

denervate the FDM and ODM by performing a Hubertype transfer of the ADM because their innervation may

depend (10 of 31 hands) on the arborization of a single

motor nerve. The arterial pedicle to the hypothenar muscles

was less variable and, when present, was in the canal in 22

of 23 hands. On average, the hypothenar muscle, nerve,

and nearest artery were separated by 8.3 mm (27).

Innervation of Palmaris Brevis. In the type A division (one

motor and one sensory branch), the palmaris brevis is innervated by a branch that originates from the ulnar division of

the sensory branch, and in the type B division (one motor and

two sensory branches), the palmaris brevis branch originates

from the most ulnar of the two sensory branches.

Sensory Branch Divisions. Type A Ulnar Division. In the

type A ulnar nerve division, the sensory branch first supplies the palmaris brevis (see preceding discussion) and the

skin overlying it (or the branch to the palmaris brevis may

originate from the ulnarmost nerve after division of the sensory branch into two), and then divides into two branches,

an ulnar branch, which forms the proper palmar digital

nerve to the ulnar side of the small finger, and a radial

branch, which after a short distance gives off a communicating branch that joins the ulnarmost branch of the

median nerve. It is the radial branch that forms the common palmar digital nerve of the fourth interosseous space

and subsequently divides into two terminal branches to

form the PDN to the radial side of the small finger and the

ulnar side of the ring finger.

Type B Ulnar Nerve Division. In the type B ulnar nerve

division, the most ulnar of the two sensory divisions gives

off the palmaris brevis branch and then continues to form

the proper palmar digital nerve to the small finger, whereas

the radial branch gives off the communicating branch and

then divides into the proper digital branches to the radial

side of the small finger and the ulnar side of the ring finger.

Communicating Branch. This branch courses from the

common digital nerve in the fourth interosseous space

(ulnar nerve origin) to the common digital nerve in the

third interosseous space (median nerve origin) (Fig. 10.34;

see Fig. 10.30). In two separate studies of 50 cadaver palms

each, this communicating branch was present in 80% and

92% (59,61). This communicating branch was located 38

mm distal to the bistyloid line of the wrist (59). Most often,

this communicating branch gave fibers to the radial digital

nerve of the ring finger, and in 20% of the dissections the

communicating branch gave fibers to both opposing sides

of the long and ring fingers. The diameter of the branch

averaged 25% of a PDN’s diameter at the finger base. Its

course often parallels the superficial palmar arterial arch,

and it may be at risk during carpal tunnel release or in

surgery along the fourth ray axis (61).

Somewhat similar findings were noted by Ferrari and

Gilbert, who found a 90% incidence in 50 cadaver palms

(62). They noted the proximity of the communicating branch

to the distal margin of the TCL and its consequent risk in

carpal tunnel surgery. Based on surface landmarks, these

10.1 Palmar Hand 579

authors described a triangular area on the hypothenar eminence of the palm wherethe nerve can be found. This area was

noted to extend from the middle half of the hypothenar eminence and is limited distally by the proximal palmar crease

and on the radial side by the longitudinal crease between the

thenar and hypothenar eminence. They noted that the nerve

always crossed the longitudinal axis from the ring finger.

Clinical Significance of the Communicating Branch. Awareness of this branch explains sensory findings that do not

conform to the classic 31

⁄2 to 11

⁄2 median–ulnar supply to the

fingers. This may explain persistent sensibility in the long

finger after complete laceration of the median nerve at the

wrist. Similarly, if a lacerated communicating branch is

overlooked, there will be permanent sensory loss even if

good recovery occurs in adjacent nerve repairs. This nerve

may be at risk with carpal tunnel release, ring finger flexor

tendon surgery, and Dupuytren’s fasciectomy. Unrecognized injuries or lacerations to this nerve may explain some

instances of palmar pain commonly attributed to nerve

traction or scarring (61,62).

Deep (Motor) Branch of the Ulnar Nerve

The course of the deep branch into the palm has been variously described as passing between the origin of the FDM

and ODM (1) or beneath the proximal origin of the FDM

(28) (Fig. 10.35 see Fig. 10.33). It then courses around the

ulnar and distal aspect of the base of the hook process of the

hamate. The proximal edge of the FDM often (14 of 23

cases) demonstrates a fibrous arcade where the motor branch

may become entrapped (28). It then traverses the hand

accompanied by the deep arterial arch, palmar to the flexor

580 Regional Anatomy

FIGURE 10.34. Communicating branch of the ulnar nerve. A: Fresh cadaver dissection showing

communicating branch from the ulnar common digital nerve in the fourth interosseous space

(green marker) to the common digital nerve in the third interosseous space (blue marker). Its

course often parallels the superficial palmar arterial arch, and it may be at risk during carpal tunnel release or in surgery along the fourth ray axis. B: This nerve may be found in a triangular area

on the hypothenar eminence and palm bounded distally by the proximal palmar crease and on

the radial side by the longitudinal crease between the thenar and hypothenar eminence.

A B

tendons. It innervates the ring and small finger lumbricals,

the palmar and dorsal interossei, the adductor pollicis, and

the deep head of the FPB. The motor branch enters the radial

one-half of the hand through the interval between the transverse and oblique heads of the adductor pollicis (1).

Muscles of the Hand

The muscles of the hand may be divided into three groups

based on their relative and geographic location: (a) thenar, (b)

hypothenar, and (c) intrinsic. Although all the muscles contained in the hand and thumb may be considered as intrinsic

muscles, for purposes of discussion in this section, the intrinsic muscles are considered to be the lumbrical and

interosseous muscles. The arbitrary nature of this division

may be subject to criticism; for example, the ADM that

forms the ulnar lateral band of the small finger is structurally

and functionally similar to a deep head of the dorsal

interosseous. Except for the radial two lumbricals, the APB,

the OP, and the superficial head of the FPB, these hand muscles usually are innervated by the ulnar nerve. Although these

muscles have been grouped according to their location in the

hand, clinically, as in injury or disease, they are dealt with as

innervation groups, and thus ulnar nerve palsy is a distinct

entity that does not necessarily match the previously

described geographic or anatomic muscle compartments.

Principles of Muscle Insertion/Function and

Innervation

The DI muscle has an insertion into bone as well as an

insertion into the lateral bands, with both insertions

demonstrating a variable incidence. Salisbury, and later

Eyler and Markee, delineated the insertions and functions

of the DI and noted the fact that the DI had two separate

components (dorsal and palmar), but that this separation

was not always clearly apparent (63,64). Salisbury, in support of this concept, quoted Meckel’s law, which states that

a muscle may have only one function. Hepburn, in 1892,

also noted separation of the DI into dorsal and palmar com10.1 Palmar Hand 581

FIGURE 10.35. The deep (motor) branch of the ulnar nerve. Note the course of the deep branch

into the palm beneath the proximal origin of the flexor digiti minimi. It then courses around the

ulnar and distal aspect of the base of the hook process of the hamate and traverses the hand palmar to the flexor tendons. It innervates the ring and small finger lumbricals, the palmar and dorsal interossei, the adductor pollicis, and the deep head of the flexor pollicis brevis. The motor

branch enters the radial one-half of the hand through the interval between the transverse and

oblique heads of the adductor pollicis.

ponents, and further noted separate nerve branches to the

two components (65). Eyler and Markee, using microdissection, found distinct nerve fibers to the dorsal and deep

components of the DI muscles (64). Eyler and Markee

noted that the classic electrophysiologic experiments of

Duchenne demonstrated the presence of the two components of the DI. Duchenne noted abduction of the finger

with application of moderate current to the medial

interosseus, whereas stronger current caused flexion of the

MCP joint and extension of the interphalangeal joints.

Although Duchenne attributed the latter action to the lumbrical, it was most likely due to stimulation of the motor

endplate of the palmar component of the DI (64). These

findings illustrate the fact that muscles that appear to be

one unit may, in fact, represent two or more functional

units. Prime examples would be the second DI, in which

the bipennate dorsal (most superficial or dorsal) component

inserts into the base of the proximal phalanx and the deep

(more palmar) component inserts into the lateral band, and

the three components of the adductor pollicis (see discussion of adductor pollicis, later), which insert into the proximal phalanx of the thumb, the ulnar sesamoid, and the

extensor expansion, respectively. Eyler and Markee noted

that all primates, except humans, have seven volar

interosseous muscles. In humans, the first, third, fourth,

and sixth palmar interossei are anatomically parts of the

first, second, third, and fourth dorsal interossei, respectively. Thus, the second, fifth, and seventh interossei are

those muscles that now commonly are referred to as palmar

interossei one, two, and three in the human hand. These

findings give weight to the concept that the deep components of the DI muscles might well be placed in the same

category as the palmar interossei because they both insert

into the lateral bands, share a unipennate form, and act as

primary extensors of the interphalangeal joints and secondarily as flexors of the MCP joints (66). These findings suggest that muscles should be considered as functional units

based on their action or movement produced rather than by

their location. Although many muscles have been named

based on their function, we often are constrained by names

that reflect long-standing usage and familiarity.

Thenar Muscles

The thenar muscles are the APB, the OP, the FPB, and the

adductor pollicis (Fig. 10.36).

582 Regional Anatomy

FIGURE 10.36. (A,B) Thenar muscles. The four thenar muscles are the abductor pollicis brevis;

the opponens pollicis; the flexor pollicis brevis; and the adductor pollicis.

A B

Abductor Pollicis Brevis

The APB, the most superficial of the thenar group, arises

mainly from the TCL, although a few fibers may arise from

the tubercles of the scaphoid and trapezium. It inserts into

the radial side of the base of the proximal phalanx of the

thumb and into the dorsal expansion of the thumb.

Although its main function is to abduct the thumb, it also

may act to extend the interphalangeal joint of the thumb

because of its insertion into the dorsal expansion.

Opponens Pollicis

Immediately beneath the APB is the OP, which arises from

the TCL and the tubercle of the scaphoid to insert on a

large portion of the palmar (radial) surface of the thumb

metacarpal. The OP acts as a flexor and abductor of the

thumb.

Flexor Pollicis Brevis

The FPB has a superficial and deep portion. The superficial

portion arises from the distal aspect of the TCL and the distal part of the tubercle of the trapezium and inserts on the

radial side of the base of the proximal phalanx of the

thumb. The deep portion arises from the trapezoid and capitate bones and from the palmar ligaments of the distal

carpal row and inserts on the ulnar side of the base of the

proximal phalanx of the thumb. The FPL tendon passes

between the two heads of the FPB. The FPB flexes the

MCP joint of the thumb.

Adductor Pollicis

The adductor pollicis has transverse, oblique, and accessory

heads (66). The triangular (or perhaps trapezoid) transverse

head arises from the palmar surface of the distal two-thirds

of middle finger metacarpal and inserts into the ulnar base

of the proximal phalanx of the thumb by a short tendon of

insertion. The similarly shaped oblique head arises from the

capitate bone and the palmar bases of the index and middle

finger metacarpals, the palmar ligaments of the carpus, and

the sheath of the FCR tendon. It inserts into the ulnar

sesamoid bone in the palmar plate at the MCP joint of the

thumb. The accessory head arises dorsal and radial to the

oblique head from the base of the index metacarpal and

inserts into the ulnar aspect of the dorsal thumb expansion

adjacent to the MCP joint.

Hypothenar Muscles

The hypothenar muscles are the palmaris brevis, the ADM,

the FDM, and the ODM (Fig. 10.37).

Palmaris Brevis

The palmaris brevis is a thin, quadrilateral muscle on the

proximal aspect of the hypothenar eminence. Its origin is

from the TCL and the ulnar border of the palmar fascia,

and it is attached to the skin on the ulnar border of the

hand. It is superficial to the ulnar artery and nerve. Its

action is to assist in cupping the hand.

Abductor Digiti Minimi

The ADM arises from the pisiform bone, the tendon of the

FCU, and the pisohamate ligament. It attaches to the ulnar

side of the proximal phalanx of the small finger and forms

the ulnar lateral band of the small finger, which ends in the

dorsal digital expansion. As its name implies, it acts as an

abductor of the small finger and also has an intrinsic function through its attachment to the hood. Structurally and

functionally, it is similar to a deep head of the dorsal

interosseous.

Flexor Digiti Minimi

The FDM lies to the radial side of the ADM and arises

from the convex surface of the hook process of the hamate

and the adjacent TCL. It inserts into the ulnar side of the

base of the proximal phalanx of the small finger. The FDM

acts as a flexor of the small finger MCP joint.

10.1 Palmar Hand 583

FIGURE 10.37. The hypothenar muscles. The four hypothenar

muscles are the palmaris brevis; the abductor digiti minimi; the

flexor digiti minimi; and the opponens digiti minimi.

Opponens Digiti Minimi

The ODM, a narrow triangular muscle, lies under cover of

the ADM and FDM in its middle and distal thirds and

arises from the convexity of the hook process of the hamate

and the adjacent portion of the TCL. It inserts along the

ulnar and palmar aspect of the small finger metacarpal. The

ODM flexes the small finger metacarpal and to some extent

rotates (supinates) the small finger metacarpal into the position of opposition.

Intrinsic Muscles

Interosseous Muscles

The interosseous muscles are located between the

metacarpal shafts and are either dorsal or palmar. Some

anatomists have concluded that there are three palmar

interosseous muscles, whereas others have described the

presence of four palmar interosseous muscles. The controversy involves the presence or absence of a palmar

interosseous in the first web space. The convention adopted

in this text is that there are three palmar and four dorsal

interosseous muscles. The DI are divided into superficial

and deep components. In general, the superficial components of the DI insert into bone; the deep components

(along with the palmar interosseous), except for the first DI,

insert into the extensor hood. The details of comparative

insertion percentages into bone or extensor hood are discussed later (64).

Dorsal Interosseous. The DI muscles are represented by

four bipennate muscles that arise from the opposing sides of

two metacarpal bones, beginning in the thumb–index finger web space and ending in the ring–small finger intermetacarpal space (Figs. 10.38 and 10.39). Each DI muscle

584 Regional Anatomy

FIGURE 10.38. Superficial dorsal interosseous (DI). In general, the superficial head of the first

and second DI inserts by means of a tendon into the radial base of the proximal phalanx of the

index and middle fingers, respectively, whereas the third and fourth insert into the ulnar base of

the middle and ring fingers. The comparative percentages of insertions of the dorsal interossei

into bone of the proximal phalanx are noted.

has a superficial and deep head (see prior discussion).

Although Smith has declared that the third DI has only a

deep head, the assumption made in this text is that the third

DI has both a superficial and a deep head (67). The use of

the terms superficial and deep in reference to the component

portions of the DI may result in some confusion because

some authors (66,68) have viewed these muscles from the

palm, whereas others (67) have viewed these muscles from

the dorsum of the hand. The convention adopted in this

text is that the most dorsal component of the DI is termed

the superficial, whereas the deep portion is, as the name

implies, deep or palmar to the dorsal (superficial component) and therefore termed deep. This convention seems

appropriate because these are DI muscles that are most easily viewed and approached surgically from the dorsum.

Linscheid et al. noted that it is not always possible to

cleanly or easily separate the superficial and deep heads by

dissection; they noted longer muscle fiber length in the

deep component compared with the superficial component

and an oblique direction of the superficial fibers compared

with the longitudinal course of the fibers in the deep component (66). Thus, differences in fiber length and direction,

and insertions, support the concept that the DI does, in

fact, have two distinct components and functions. Similar

findings of a superficial and deep component of the DI

were made by Salisbury, and later by Eyler and Markee

(63,64). Salisbury, in support of this concept, quoted

Meckel’s law, which states that a muscle may have only one

function (63). Hepburn, in 1892, also noted separation of

the DI into dorsal and palmar components, and further

noted separate nerve branches to the two components (65).

Eyler and Markee, using microdissection, found distinct

nerve fibers to the dorsal and deep components of the DI

muscles (64). Eyler and Markee noted that the classic elec10.1 Palmar Hand 585

FIGURE 10.39. Deep dorsal interosseous (DI) muscles (superficial components of the DI have

been partially removed).

trophysiologic experiments of Duchenne demonstrated

(perhaps unwittingly) the presence of the two components

of the DI when Duchenne noted abduction of the finger

with application of moderate current to the medial

interosseus, whereas stronger current caused flexion of the

MCP joint and extension of the interphalangeal joints.

Although Duchenne attributed the latter action to the lumbrical, it was most likely due to stimulation of the motor

endplate of the palmar component of the DI (64).

Superficial Head. In general, the superficial heads (the most

dorsal of the two components) of the first and second DI

insert by means of a tendon into the radial base of the proximal phalanx of the index and middle fingers, respectively,

whereas the third and fourth insert into the ulnar base of

the middle and ring fingers. The first DI inserts almost

exclusively into bone and may have a small and variable

deep belly component. The third DI is the least likely to

have a bony insertion (see following discussion regarding

comparative percentages of insertion into bone or hood).

The dorsal component of the DI is bipennate and originates from the two adjacent sides of the metacarpal. This

portion of the DI occupies approximately the dorsal onehalf of each interosseous space.

Deep Head. In general, the deep heads of the DI each form

a lateral band at the level of the MCP joint, and over the

middle of the proximal phalanx send fibers that join similar

fibers from the lateral band on the opposite side of the finger. The palmar component of each DI is phylogenetically

a palmar interosseous, is invariably fused to its dorsal component, and may be partially fused to the palmar interossei.

The deep component of the DI is roughly fusiform and

often multipennate. In the index finger, the tendon of the

variably present deep component of the first DI may fuse

with the superficial component to attach to the proximal

phalanx, or the deep component may be a distinct muscle

with insertion into the hood (66). If present in this configuration, it, along with the lumbrical, forms the radial component of the hood that joins the ulnar counterpart (lateral

band) of the first palmar interosseous to form the extensor

expansion. In the middle finger, the radial lateral band is

formed by the deep portion of the second DI, and the ulnar

lateral band from superficial and deep components of the

third DI. In the ring finger, the radial lateral band is from

the second palmar interosseous, and the ulnar lateral band

from the deep head of the fourth DI. In the small finger, the

radial lateral band from the third palmar interosseous joins

the lateral band extension of the ADM to form the exten586 Regional Anatomy

FIGURE 10.40. Palmar interosseous muscles. Comparative percentages of insertion

into the extensor hood of the palmar

interossei are noted. The balance of the

insertion of the various muscles, if not

100%, is into bone.

sor expansion. The first and largest DI muscle is sometimes

called the abductor indicis. In the distal third of the proximal phalanx, oblique fibers (spiral fibers) from the lateral

bands continue distally to insert onto the lateral tubercles at

the base of the middle phalanx and act to extend the middle phalanx.

Comparative Percentages of Insertion into Bone of the Dorsal

Interossei. Eyler and Markee (64) studied the comparative

percentages of insertions of the DI muscles into bone of the

proximal phalanx and noted the following approximate percentages (see Fig. 10.38) first DI (index), 100%; second DI

(middle), 60%; third DI (middle), 6%; fourth DI (ring),

40%. They noted a 90% bony insertion of the ADM. Only

the first DI was completely inserted into bone. The balance

of the insertion of the various muscles, if not 100%, was

into the extensor hood. Their results were similar to those

of Salisbury.

Function of Dorsal Interosseous. Superficial Heads. The

superficial heads of the DI abduct the fingers from an imaginary line through the central axis of the middle finger and

weakly flex the proximal phalanx of the index, middle, and

ring fingers. Because the DI has no bony insertion on the

small finger, abduction in this digit is performed by the

ADM and flexion by the FDM.

Deep Heads. The deep heads flex and abduct the proximal

phalanx and through the spiral or oblique fibers of the lateral bands extend the middle phalanx. Extension of the distal phalanx is from the distal extension of the lateral bands

(the conjoined tendon).

Palmar Interosseous. The palmar interosseous muscles are

unipennate muscles (Fig. 10.40). Based on the chosen convention of three, rather than four, palmar interosseous muscles, the first palmar interosseous arises from the ulnar side

of the index metacarpal and is inserted into the extensor

expansion on the same side of the index finger, forming the

ulnar lateral band of the index finger. Transverse fibers arch

over the dorsum of the proximal phalanx to join similar

fibers from the opposite lateral band. The second palmar

interosseous arises from the radial side of the ring finger

metacarpal and inserts into the extensor expansion on the

same side of the ring finger. It forms the radial lateral band

of the ring finger and also sends transverse fibers over the

proximal phalanx of the ring finger. The third palmar

interosseous arises from the radial side of the small finger

10.1 Palmar Hand 587

FIGURE 10.41. The lumbrical muscles. The

usual pattern of insertion of the lumbricals is

into the radial side of the extensor hood, as

demonstrated by the second lumbrical.

metacarpal and inserts almost exclusively into the extensor

expansion on the radial side of the small finger, forming the

radial lateral band of the small finger and sending fibers

dorsally to join the opposite lateral band. The third is the

only palmar interosseous that has any significant insertion

into bone. Except for the third, none of the palmar

interosseous muscles insert into bone in the proximal phalanx, but all three of the palmar interossei send oblique or

spiral fibers to insert on the lateral tubercle of the middle

phalanx. In general, the three palmar interosseous muscles

“face” the middle finger metacarpal (64). The ulnar lateral

band of the small finger is formed by the tendinous continuation of the ADM.

Comparative Percentages of Insertion into the Extensor Hood of

the Palmar Interossei. Eyler and Markee (64) studied the

comparative percentages of insertion of the palmar interossei into the extensor hood and noted the following approximate percentages (see Fig. 10.40): first palmar interosseous

(index), 100%; second palmar interosseous (ring), 100%;

third palmar interosseous (small), 90%. The balance of the

insertion of the various muscles, if not 100%, was into

bone. Their results were similar to those of Salisbury (63).

Function of Palmar Interosseous. Based on their

anatomic position and insertions, it is easy to recognize that

these muscles act as adductors of their respective fingers

toward the middle finger (the central axis), flex the proximal phalanx, and extend the middle phalanx through their

distal continuation. Because the deep portions of the distal

and the palmar interossei most often are inserted into the

hood mechanism, their action depends to some extent on

the position of the MCP joint and thus of the hood. When

the MCP joint is in extension, the hood is adjacent to the

MCP joint, and the interossei are under tension and extend

the middle and distal phalanges. When the MCP joint is in

flexion, the hood is more distal and acts as a sling about the

dorsal and proximal aspect of the proximal phalanx; when

the interossei contract, they act as flexors of the MCP joint.

When the MCP joint is flexed, the interossei cannot extend

the middle and distal phalanges (21).

Lumbrical Muscles

The lumbrical muscles are comparatively small intrinsics

that arise from the flexor digitorum profundus (FDP) tendons (Fig. 10.41). The first and second lumbricals arise

from the radial and palmar surfaces of the index and long

finger FDP tendons, the third from the adjacent sides of the

long and ring finger FDP, and the fourth from the adjacent

sides of the ring and small finger FDP tendons. The first

and second lumbricals are unipennate and the third and

fourth bipennate. The tendon of each lumbrical passes palmar to the transverse metacarpal ligament and, in general,

joins the radial lateral band of each finger.

Insertion of the Lumbricals. The usual pattern of insertion of the lumbricals is into the radial side of the extensor

hood, as demonstrated by the second lumbrical. Exceptions

in the remaining lumbricals noted by Eyler and Markee

included: first lumbrical, small bony insertions into the

index; third lumbrical, insertion into the ulnar side of the

long finger, bifid insertion (radial side of ring finger and

ulnar side of long finger), bony insertion; fourth lumbrical,

ulnar side of ring finger, bifid insertion (radial side of small

588 Regional Anatomy

FIGURE 10.42. Comparative angle of attack of the

interossei and lumbrical muscles, after Eyler and Markee

(64).

finger, ulnar side of ring finger), and part into bone and

part into expansion (64).

Function of the Lumbricals. Various functions have been

ascribed to the lumbricals, including the initiation of flexion

of the MCP joints, extension of the interphalangeal joints,

flexion of the MCP joint, radial deviation of the fingers, and

pulling the FDP distally to allow the interphalangeal joints to

be more easily extended (64). Pulling distally on the FDP

when this muscle is at rest permits a reduction in the viscoelastic resistance of the FDP and indirectly facilitates the

action of the common extensor on the middle and distal phalanges (21,69). In contrast to the interossei, the lumbricals

may extend the middle and distal phalanges with the MCP

joint in flexion. In a low ulnar nerve lesion, the lumbricals acting alone may stabilize the MCP joints and extend the interphalangeal joints of the index and middle fingers. When the

lumbrical contracts, it pulls the FDP distally and the lateral

band proximally, resulting in decreased force in the FDP,

which allows more effective extension of the PIP and DIP

joints by the lumbrical. When the lumbrical and FDP contract together, interphalangeal joint flexion may be limited. As

the tips of the fingers close in a grasp, lumbrical tension

increases, and when grasp is almost complete, the lumbricals

contribute most to flexion. An important function of the lumbricals is to stabilize the MCP joint and to contribute to the

force of the final phase of grasp (64). Perhaps their most

important function is interphalangeal extension, after which

they may act as MCP flexors (21,70).

Intrinsic Muscle Function Based on the Comparative

Angle of Attack of the Interossei and Lumbricals

Eyler and Markee described the angle of attack of the various components of the intrinsics (Fig. 10.42) and noted the

following:

1. The tendon of the dorsal component of the DI passes

almost directly over the axis of rotation of the joint and

thus may extend, flex, or abduct the phalanx; its angle of

attack is 0 to 5 degrees.

2. The palmar components of the dorsal and the palmar

interossei attack the joint well below the axis and thus

are capable of flexing the MCP joint more strongly, as

well as of extending the interphalangeal joints; their

angle of attack is 20 to 25 degrees.

3. Each lumbrical approaches the MCP joint palmar to the

transverse metacarpal ligament and is mechanically best

suited to initiate flexion of the MCP and to insert force

on the joint when in flexion; their angle of attack is 35

degrees (64).

Architectural Design of the Human Intrinsic Hand

Muscles

Definition. The architecture of skeletal muscle is defined

as the arrangement of muscle fibers relative to the axis of

force generation (71).

Important Architectural Properties of Intrinsic Hand

Muscles. The most important architectural properties of

muscle are muscle length (ML), muscle fiber length (FL),

and physiologic cross-sectional area (PCSA). Muscle excursion and velocity are directly proportional to FL, and isometric muscle force is directly proportional to the PCSA

(72). The intrinsic muscles of the hand are important for

efficient and balanced hand function, and a knowledge of

their architectural specialization has implications for tendon transfer, biomechanical modeling, prothesis design,

and analysis of normal function (72).

Intrinsic Muscle Lengths/Fiber Lengths. Based on a study

of the intrinsic muscles in nine hands, Jacobson et al. noted

that intrinsic MLs were relatively similar to one another

(average ML was 65 mm, compared with extrinsic average

ML of 162 mm), which the authors interpreted as representing a space constraint in the hand. However, specialized

architectural designs were noted: lumbrical muscles had an

extremely high FL/ML ratio, implying a need for high

excursion. Lumbrical muscle fibers extended 85% to 90%

of the ML, which represented a very high FL/ML ratio.

Lumbrical muscle FLs were similar to the FLs of the FDP,

FDS, and ECRB muscles. The result of such an arrangement in the lumbrical is a flatter, broader length–tension

curve that implies a relatively constant contractile force over

a long range of FLs, depending on the position of the FDP

tendon. Thus, it can be argued that long lumbrical muscle

fibers might facilitate active muscle contraction, even during FDP contraction, by allowing the lumbrical origin to

move without large changes in sarcomere length. If lumbrical muscle FLs were short, FDP excursion could stretch the

lumbrical sarcomeres to the point where they would be

unable to generate active force (72). The FL/ML ratio can

be seen as a relative measure of design preference for excursion (high ratio) or force (low ratio). The intrinsics have relatively high FL/ML ratios, representing a design bias

toward excursion and velocity production and a relative bias

against force production. Although the interosseous muscles have the lowest FL/ML ratio, it is surprisingly high for

their pennation. Their FL appears to represent a minimum

that is required to meet their functional requirements of

excursion and strength. Although Jacobson et al. did not

measure the differences between the superficial and deep

components of the DI, Linscheid et al. noted a distinct difference in fiber length and orientation between the two

components, which would support the concept that two

components of the DI have different FLs and thus different

excursions (66).

Physiologic Cross-Sectional Area. The most variable measurement between the various intrinsic muscles is their PCSA.

The PCSA is proportional to maximum isometric tension.

The lumbrical PCSA is 0.1 cm compared with the adductor

pollicis PCSA of almost 2 cm (72). The first DI and adductor

10.1 Palmar Hand 589

pollicis had PCSAs comparable with those of extrinsic muscles

and much greater than those of the other intrinsic muscles.

The mass of the adductor pollicis (1.94 g) was the largest of

the intrinsic muscles, followed by the DI, palmar interosseous,

thenar, and hypothenar muscles. The lumbrical muscles had

the lowest muscle masses in the hand, ranging from 0.23 to

0.57 g. The interosseous muscles had relatively high PCSAs

with low FL/ML ratios, suggesting their adaptation for high

force production and low excursion. Generally, the PCSAs of

the intrinsics were the lowest of all those measured in the

upper limb, with the exception of those muscles that had no

extrinsic synergist. For example, the adductor pollicis and first

DI are the primary providers of their functions in the hand

and are responsible for key pinch, which requires the ability to

generate high forces (72).

Extrinsic Extensors and Dorsal Aponeurosis

Any discussion of the intrinsic muscles and their function

would be incomplete without including their relationship

to the dorsal aponeurosis and extrinsic extensors because

functionally, the two systems cannot be separated (Figs.

10.43 and 10.44). It was Landsmeer in 1949 (73) who

stated that the dorsal aponeurosis gave the morphologic

basis for the integration and coordination of the extensor

and interosseous muscles.

590 Regional Anatomy

FIGURE 10.43. Relationship of the extrinsic extensors, dorsal aponeurosis, and intrinsic tendons.

The extensor digitorum communis (EDC) and the index

and small finger proprius tendons join the extensor expansion at the MCP joint (74). These tendons are maintained

over the apex of the MCP joint by a substantial dorsal sling

of transverse fibers, the sagittal band, which invest the tendon dorsally and pass palmarward on each side of the MCP

joint to attach to the palmar plate and the transverse

metacarpal ligament. The extensor mechanism at the level

of the proximal aspect of the finger is composed of a layered

criss-cross fiber pattern, which changes its geometric

arrangement as the finger flexes and extends. This arrangement allows the lateral bands to be displaced volarly in flexion and to return to the dorsum of the finger in extension

(75). The sagittal band acts as a static tether to prevent

radial or ulnar displacement of the extensor mechanism and

also acts as a dynamic tether that allows proximal and distal

gliding of the extensor tendons during finger flexion and

extension. The sagittal bands are positioned between the

tendons of insertion of the superficial and deep components of the DI musculotendinous unit. This arrangement

allows freedom of movement to the sagittal band in the

plane between the two components of the DI and avoids

impingement between the sagittal band and the lateral band

formed by the deep component of the DI or the palmar

interosseous.

Function of the Extrinsic Extensors

Contraction of the extensors results in extension of the

proximal phalanx by the proximal phalangeal attachments

of the sagittal bands. Hyperextension is avoided by the tethering effect of the palmar plate and the intrinsic muscles,

which insert into the extensor expansion.

Distal Anatomy of the Extrinsic Extensors

Distal to the MCP joint, the extensor tendon divides into

three components: the central slip, which inserts into the

dorsal base of the middle phalanx, and two lateral slips that

join the lateral bands at the distal aspect of the proximal

phalanx. Smith has appropriately called this union of the

intrinsic muscle lateral bands and the lateral slips from the

extensor tendon the conjoined lateral bands (67). The lateral

bands, at approximately the middle portion of the middle

phalanx, send slips to the central tendon. However, this

exchange of slips between the central portion of the extensor tendon and the lateral bands (and vice versa) is best

appreciated in special anatomic preparations, and may not

always be readily apparent in the operating room. The conjoined lateral bands fuse over the middle phalanx to form

the terminal tendon, which inserts into the dorsal base of

the distal phalanx. The transverse retinacular ligament,

which spans between the lateral bands and the flexor canal

at the PIP joint, prevents dorsal migration of the lateral

bands (Fig. 10.45). The triangular ligament maintains the

conjoined lateral bands dorsally over the proximal aspect of

the middle phalanx.

10.1 Palmar Hand 591

FIGURE 10.44. Extensor mechanism of a small finger (fresh

cadaver dissection). The point of the distal arrow indicates the

oblique retinacular ligament adjacent to the transverse retinacular ligament. The proximal arrow points to the sagittal band.

(From Milford LW Jr. Retaining ligaments of the digits of the

hand: gross and microscopic anatomic study. Philadelphia: WB

Saunders, 1968:35, with permission.)

FIGURE 10.45. The transverse retinacular ligament (fresh

cadaver dissection). The tip of the angled probe is beneath the

transverse retinacular ligament. Cleland’s ligaments arise palmar

to this ligament and project proximally and distally. (From Milford LW Jr. Retaining ligaments of the digits of the hand: gross

and microscopic anatomic study. Philadelphia: WB Saunders,

1968:48, with permission.)

Oblique Retinacular Ligament

The oblique retinacular ligament (ORL) is discussed in this

section because of its interaction with the intrinsic muscle

system (Figs. 10.46 and 10.47; see Fig. 10.43). This structure was first described by Weitbrecht in 1742 and named

retinaculum tendini longi, indicating its tendinous rather

than ligamentous character (6,76,77). Haines, Landsmeer,

and others have described its structure and functions

(68,73,78). Milford noted that Landmeer in 1949 called

attention to this ligament, followed 1 year later by a similar

report by Haines, who called this structure the link ligament. Haines did not know of Landsmeer’s publication

until after his paper was written (77). Neither author apparently knew of Weitbrecht’s description of a similar structure

over 200 years previously until Kaplan pointed it out in his

second edition of Functional and Surgical Anatomy of the

Hand (63). The ligament is present on both sides of the finger, and its proximal origins are from the outer and distal

aspect of the A2 pulley and the lateral surface of the distal

third of the proximal phalanx. The ORL origins may be

covered at times by the lateral bands (77). The ligament

passes distally parallel to the lateral bands and across the

region of the PIP joint, where it is deep to the transverse

retinacular ligament, and then inserts variably into the lateral bands at approximately the level of the PIP joint or into

the terminal tendon in the distal half of the middle phalanx

(21,77). Milford noted that sometimes these fibers could be

seen to continue at the lateralmost part of the lateral band

as it inserted into the distal phalanx (77). It is consistently

palmar to the PIP and dorsal to the DIP joint axis of rotation. The ORL is said to coordinate movement of the interphalangeal joints because extension of the PIP joint places

the ORL under tension and acts as a dynamic tenodesis to

aid the conjoined or terminal tendon in extension of the

DIP joint. Based on this concept, the ORL is placed under

tension with DIP joint flexion. Thus, it is stated that the

ORL does not permit easy active or passive flexion of the

DIP joint when the PIP joint is in extension (68). This may

be demonstrated on one’s own finger by noting that active

flexion of the DIP usually is not possible until the PIP joint

is flexed (unless the PIP joint is supported in extension to

allow the powerful FDP to overcome the normal situation).

Harris and Rutledge, based on their study of the extensor

mechanism and its relationship to the ORL, concluded that

in the normal finger, extension of the DIP joint was performed entirely by the terminal extensor tendon (74). They

considered the ORL to be a stay or retaining ligament that

maintained the extensor on the dorsum of the finger.

Although the structure and extent of the ORL, and thus its

functional effect, may vary from finger to finger, when

thickened and contracted it may play a role in PIP and DIP

joint contracture, as noted in boutonniere deformity (21).

Clinical Significance of the Intrinsic Muscles

Although the specific function of each of the intrinsic,

thenar, and hypothenar muscles has been given in the preceding section, a broader and perhaps more useful understanding of their significance in hand function may be had

by (a) noting their overall function in the normal hand, (b)

noting the resultant hand deformities with intrinsic muscle

weakness or absence of function, and (c) noting the patterns

of hand deformity with contracture of the intrinsics.

Intrinsic Muscle Function in the Normal Hand

Strength and balance are the key terms that characterize the

function of the intrinsics in the hand. The interossei, lumbricals, FDM, and the bony insertion portion of the ADM

are flexors of the proximal phalanges, and grip strength may

be diminished if they are weak or absent (67).

592 Regional Anatomy

FIGURE 10.46. The oblique retinacular ligament (ORL; fresh

cadaver dissection). The angled probe is tenting up the transverse retinacular ligament and the hook to the left places tension on the ORL. (From Milford LW Jr. Retaining ligaments of the

digits of the hand: gross and microscopic anatomic study.

Philadelphia: WB Saunders, 1968:49, with permission.)

FIGURE 10.47. Origin of the oblique retinacular ligament (ORL;

fresh cadaver dissection). The white arrow points to the origin of

the ORL near the distal end of the second annular pulley. The

hook is retracting the extensor mechanism dorsally. The fingertip is to the left. (From Milford LW Jr. Retaining ligaments of the

digits of the hand: gross and microscopic anatomic study.

Philadelphia: WB Saunders, 1968:50, with permission.)

Weakness or loss of intrinsic muscle function results in

an imbalance of the extrinsic flexors and extensors of the

three finger joints and a so-called claw deformity results at

rest. The absent function of the intrinsics as flexors of the

proximal and extensors of the middle and distal joints

results in hyperextension of the proximal joints and acute

flexion of the middle and distal joints during attempts at

extension of the fingers or grasp because of the unopposed

action of the EDC, FDS, and FDP, respectively (Fig.

10.48). Although so-called hook grasp, as in holding a

briefcase handle, is relatively undisturbed in intrinsic palsy,

all forms of grasp or pinch that require simultaneous MCP

flexion and interphalangeal joint extension are awkward, if

not impossible.

Patterns of Deformity and Functional Loss Due to

Intrinsic Muscle Weakness or Absence

Low Ulnar Nerve Palsy. This pattern refers to denervation

of the ulnar-innervated intrinsic muscles in the hand. Thus,

in general, the thenar muscles are spared along with the

radial lumbrical muscles. The resultant deformity is characterized by clawing of only the ring and small fingers. Clawing of the index and middle fingers would not occur

because of the median nerve innervation of the radial two

lumbricals. In addition to the clawing of the ring and small

fingers, there is loss of grip strength and abduction and

adduction of the fingers. Attempts to extend the ring and

small fingers are associated with hyperextension of the

MCP joints because of the unopposed action of the EDC.

High Ulnar Nerve Palsy. At this level, the innervation of

the FCU and FDP to the ring and small fingers is lost, in

addition to the intrinsics. The resultant effect on the fingers

is similar to the low ulnar nerve lesion, except that the clawing is less severe, but the grip loss is more significant.

Low Ulnar and Median Nerve Palsy. In this lesion, the

function of all intrinsic, thenar, and hypothenar muscles is

lost.

There is significant loss of grip strength, clawing of all

fingers, loss of abduction and adduction of the fingers, and

loss of opposition of the thumb. The loss of intrinsic flexion at the MCP joint allows the unopposed long extensors

to hyperextend the MCP joints during attempts at finger

extension. Extension of the middle and distal joints is lost,

and the unopposed action of the FDS and FDP accentuates

the claw deformity.

High Ulnar and Median Nerve Palsy. In this lesion, there

is loss of all intrinsic muscle function as well as the extrinsic flexors. Only the EDC is functional, and no claw deformity is present. When the EDC contracts, the MCP joints

hyperextend, along with extension of the interphalangeal

joints. If the median and ulnar nerves are successfully

10.1 Palmar Hand 593

FIGURE 10.48. Patterns of grasp without and with intrinsic muscle function. A, B: The so-called

claw or hook deformity due to absent intrinsic function results in inability to grasp objects such

as a ball. C: This is in contrast to normal grasp with intact intrinsic function.

A B

C

repaired, clawing may develop as the FDS and FDP are

reinnervated (67).

Intrinsic Contracture

Definition. This condition is defined as any abnormal

contracture or shortening of the lumbricals, interossei, or

lateral band.

Etiology. Primary Causes. Intrinsic contracture may be

due to central nervous system disorders with spasticity, such

as cerebral palsy or after cerebrovascular accidents. It may

be a residual of traumatic incidents that produce hematoma

or edema with subsequent contracture in the intrinsic muscles or lateral band, or traumatic incidents that produce secondary deformity such as the mallet finger. Intrinsic contracture also may be associated with inflammatory diseases

such as rheumatoid arthritis.

Secondary Causes. The lateral band may be stretched or displaced over an osteophyte or osteochondroma in the proximal phalanx, or the lateral band may be displaced dorsally

and shortened because of a chronic mallet finger deformity.

Tests for Intrinsic Muscle Contracture (Intrinsic Tightness or Bunnell Test). Zancolli (79) and Smith (67) credit

Finochietto (80) and Parkes (81) with the initial description

(Fig. 10.49).

The basic maneuver involved in testing for intrinsic contracture or tightness is to place the intrinsic muscles at their

maximum length. This is achieved by passive hyperextension of the MCP joint. The PIP joint is then passively flexed

and the degree and ease of flexion noted. If easy and complete passive flexion of the PIP joint is obtained, the test is

negative.

If, however, there is incomplete flexion of the PIP joint

in the first maneuver, the MCP joint is passively flexed and

the ease and degree of flexion of the PIP joint is again determined. If PIP joint flexion is improved when the MCP

joint is flexed, the test is considered to be positive.

Thus, in most cases of intrinsic tightness, there is less

flexion of the PIP joint when the MCP joint is held in

extension.

Other Causes of Limited Proximal Interphalangeal Joint

Flexion. If PIP joint motion is limited because of PIP joint

594 Regional Anatomy

FIGURE 10.49. A, B: The intrinsic tightness (IT) test.

A B

disease or contracture, or adhesion of the extensor tendon

over the proximal phalanx, the position of the MCP joint

will not influence PIP joint motion. If PIP joint motion is

limited because of extrinsic extensor tendon contracture or

adhesion on the dorsum of the hand, PIP joint motion will

be greater when the MCP joint is extended. In the extensor

plus syndrome, there is shortening or adherence of the

extensor mechanism proximal to the MCP joint, which

results in inability to flex the MCP and PIP joints simultaneously, although the joints can be flexed individually (82).

If flexion of the MCP joint is associated with absent or limited flexion of the PIP joint, the test is positive and is confirmed by noting improved or complete flexion of the PIP

joint with hyperextension of the MCP joint.

Intrinsic contracture may coexist with PIP joint stiffness,

extrinsic (flexor) contracture, and MCP joint subluxation

or dislocation with contracture. In MCP joint contracture,

it is impossible to compare PIP joint motion, but intrinsic

contracture nevertheless may be present.

Intrinsic “Plus” and “Minus” Hand. The terms intrinsic

plus and intrinsic minus have been used to describe the characteristic postures of the fingers with spasm or contracture

of the intrinsic muscles and absence of function of the

intrinsics due to ulnar nerve laceration or disease, respectively. The intrinsic plus deformity is seen most often in

rheumatoid arthritis, and the intrinsic minus deformity in

ulnar nerve dysfunction.

The term intrinsic plus also is used to describe the recommended position for splinting the fingers in a swollen

hand to prevent undesirable contractures. This position is

characterized by flexion of the MCP joints and extension of

the PIP joints. The rationale for this posture is discussed in

the section on Joints.

Lumbrical Plus Condition. Definition. Paradoxical

extension of the PIP joint occurs when flexion of the finger

is attempted (83).

Pathomechanics. If the profundus tendon is lacerated in the

finger, the proximal end of the tendon migrates proximally

because of the pull of its muscle belly. The lumbrical origin

is carried proximally, and this increased tension on the lumbrical may produce increased tension in the lateral band

and thus extension of the PIP joint.

This condition also may develop after amputations of the

distal phalanx. It may be noted with flexor tendon grafts that

are too long. Wrapping the lumbrical about the repair site of

a lacerated flexor tendon also may be a cause of lumbrical

plus if the lumbrical subsequently contracts or shortens.

Diagnosis. This condition may be diagnosed if the intrinsic

tightness test is positive after a tendon graft, distal phalanx

amputation, or FDP tendon repair if the patient demonstrates paradoxical extension of the PIP joint.

Author’s Comment. Although not a common condition,

lumbrical plus may provide an explanation for paradoxical

extension of the PIP joint in certain conditions.

Retinacular System

The retinacular system of the hand includes the TCL, palmar fascia, natatory ligaments, palmar and digital pulley

system, and the retaining ligaments of the fingers. In this

context, retinacular structures are defined as fibrous tissue

structures that retain or keep in place [i.e., “halter” (Latin)].

Palmar Fascia

The palmar fascia is defined as the specialized fascial structure in the central portion of the palm with longitudinal,

transverse, and vertical fibers (Fig. 10.50). It is distinguished from the fascial covering of the thenar and

hypothenar eminences by its triangular shape and thickness. The longitudinal fibers represent the distal continuation of the palmaris longus (when present). These fibers,

which begin as a conjoined apex at the base of the palm,

form bundles in the middle and distal palm that course to

the corresponding four fingers and in some instances to the

thumb. The longitudinal fibers are more or less parallel to

the deeper flexor tendons, and because of this arrangement

sometimes are called pretendinous bands. The four bundles

of longitudinally oriented fibers overlay transverse fibers in

the palm that are located at the junction of the middle and

distal thirds of the palm and over the MCP joints.

McGrouther has noted that these longitudinal fibers divide

into three layers in the distal palm (2). Layer one, the most

superficial, inserts into the skin of the distal palm and onto

the proximal aspect of the flexor sheath. Layer two splits

and passes on each side of the flexor sheath, where it continues distally as the spiral band of Gosset (84) beneath the

neurovascular bundle and natatory ligaments to insert on

the lateral digital sheet. Layer three passes on each side of

the flexor sheath to the region of the MCP joint (85). The

transverse fibers of the palmar fascia course beneath the longitudinal cords from the ulnar side of the small finger to the

radial side of the index finger. In the thumb–index finger

web space, the proximal commissural ligament (PCL) is the

radial continuation of these transverse fibers. The more distal counterpart of the PCL is the distal commissural ligament (DCL), which is more longitudinally oriented and

spans the space between the MCP joint of the thumb and

index finger (86). Both the PCL and DCL course toward

the thumb MCP joint, where they send attachments to the

undersurface of the skin in the region of the MCP joint; the

deep portion of the DCL sends fibers to attach on both

sides of the FPL sheath (87). The more longitudinal orientation of the DCL may be a factor in its more likely involvement in Dupuytren’s contracture, although both the DCL

and PCL may be involved in Dupuytren’s contracture (85).

10.1 Palmar Hand 595

The PCL and DCL usually are thinner and less noticeable

than the transverse fibers between the fingers. Both the longitudinal and transverse fibers course through the vertical

septa to reach the transverse metacarpal ligament (88). The

third component of the palmar fascia consists of the nine

vertical (sagittal) septa (the fibers of Legueu and Juvara)

(89) located deep to the transverse fibers, which form the

sides of eight canals: four of which contain the underlying

finger flexor tendons, and four adjacent canals that contain

the lumbrical muscles and neurovascular bundles. These

paratendinous septa, along with the transverse fibers of the

palmar aponeurosis, form a fibrous tunnel system that has

been described as the palmar aponeurosis pulley (90,91).

These nine vertical septa are anchored to the transverse

metacarpal ligament, palmar interosseous, and adductor

fascia. Bojsen-Moller and Schmidt noted that these vertical

septa divided the distal portion of the central palmar space

into eight canals (88). Although these vertical septa are not

596 Regional Anatomy

FIGURE 10.50. The palmar fascia,

natatory ligament, and commissural

ligaments. The transverse fibers of the

palmar fascia course beneath the longitudinal cords from the ulnar side of

the small finger to the radial side of

the index finger. In the thumb–

index finger web space, the proximal

commissural ligament (PCL) is the

radial continuation of these transverse

fibers. The more distal counterpart of

the PCL is the distal commissural ligament, which is more longitudinally oriented and spans the space between

the metacarpophalangeal joints of the

thumb and index finger. Natatory ligaments are located in the web spaces

between the fingers.

FIGURE 10.51. Distal palmar and digital fascia. The longitudinal fibers of the palmar fascia divide

into three layers in the distal palm. Layer one, the most superficial, inserts into the skin of the distal palm and onto the proximal aspect of the flexor sheath. Layer two splits and passes on each

side of the flexor sheath, where it continues distally as the spiral band beneath the neurovascular

bundle and natatory ligaments to insert on the lateral digital sheet. Layer three passes on each

side of the flexor sheath to the region of the metacarpophalangeal joint. The natatory ligaments

have transverse as well as curved fibers that follow the contour of the webs. The curved or distal

continuations of these fibers join the lateral digital sheet. The lateral digital sheet is a condensation of the superficial digital fascia on each side of the finger and receives fibers from the natatory ligament, the spiral band, and Grayson’s ligament. The retaining skin ligaments of Grayson

and Cleland stabilize the skin during flexion and extension of the finger. Grayson’s ligaments are

palmar to the neurovascular bundles and pass from the skin to the flexor tendon sheath. These

ligaments form a tube from the proximal aspect of the finger to the distal interphalangeal joint,

where the digital nerves and vessels always can be found during surgical dissection.

classically considered as part of the palmar aponeurosis, the

authors consider them to be an integral component of the

palmar fascia, and they therefore are included here.

Natatory Ligaments

These ligaments, located in the web spaces between the fingers, also are called the superficial transverse metacarpal ligament (Fig. 10.51; see Fig. 10.50). They are the superficial

counterpart to the more proximal deep transverse metacarpal ligament, which spans between the palmar plates of

the four finger metacarpals.

Author’s Comment. In my opinion, much confusion could

be avoided if the deep and superficial components of these

names were deleted, so that transverse metacarpal ligaments

and natatory ligaments were the terms used. The natatory

ligaments were aptly named by Grapow the Schwimmband

(“swim ligaments”) because of their position in the interdigital webs (86). The natatory ligaments have transverse as

well as curved fibers that follow the contour of the webs.

The DCL may be the first web space counterpart of the finger natatory ligament.

Clinical Significance of the Palmar Retinacular

System

Compression Loading/Shock Absorbing

Any discussion of the role of the palmar retinacular structures must note that these structures are only a part of a

complex tissue consortium designed to meet a variety of

functional demands. This complex three-dimensional network may be considered as a fibrous skeleton or framework

designed to assist in the hand’s mechanical functions (1,85).

Compression loading is a common force applied to the

hand and requires a system of shock absorption. In the

hand, one method of shock absorption is to contain somewhat compliant tissues such as fat or muscle in compartments that can change shape but not volume. This is amply

demonstrated in the palm, with its various layers of multidirectional fascia that contain and compartmentalize fat

and muscle while at the same time conforming to the shape

or contour of the object being grasped or manipulated.

Skin Anchorage

Skin is retained by fascial elements that allow the hand to

flex while maintaining the skin in position. The skin folds at

prominent creases that are minimally anchored, in contrast

to the skin on the adjacent sides of the crease, which possess

multiple strong anchor points. This allows the relatively

unanchored skin to fold while the anchored skin is held in

place. These fascial anchors may be vertical, horizontal, or

oblique, depending on the specific need of the skin envelope. A good example is the horizontal attachments of the

superficial fibers of the pretendinous bands, which attach to

the dermis of the distal palm. This arrangement resists horizontal shearing force in gripping actions such as holding a

hammer or golf club. The palmar aponeurosis, which

includes the nine vertical septa anchored to the deep transverse metacarpal ligament, is tensed with power grip and

thus anchors the skin to the skeleton of the hand (88).

Skeletal Stability

Although not a part of the palmar fascia, the previously

mentioned transverse metacarpal ligament that attaches to

the palmar plates of the MCP joints plays a role in main10.1 Palmar Hand 597

taining the transverse metacarpal arch, as do the transverse

fibers of the palmar fascia and the natatory ligaments.

Joint Stability

The fascial ligaments in the web space of the finger and

thumb may play a role in limiting abduction and thus may

indirectly limit the impact of potentially destabilizing forces

that might be applied to the digits.

Pulley Function

The transverse fibers of the palmar fascia, supported by the

vertical septa, form what is called the palmar aponeurosis pulley, and is discussed later in the section on the Pulley System.

Vascular Protection and Pumping Action; Nerve

Protection

Vascular structures in the palm are protected by surrounding them with substantial fibrous tissue in combination

with fat pads. When the hand is compressed, as in making

a fist, the incompressible fascia may act as a venous pumping mechanism. This is in contrast to the large dorsal veins

on the dorsum of the hand surrounded by loose areolar tissue. The nerves in the palm are protected by fascial structures, and near the base of the fingers by fat pads.

Digital Fascia

McGrouther has noted that the longitudinal fibers of the

palmar fascia divide into three layers in the distal palm (85)

(see Fig. 10.51). Layer one, the most superficial, inserts into

the skin of the distal palm and onto the proximal aspect of

the flexor sheath. Layer two splits and passes on each side of

the flexor sheath, where it continues distally as the spiral

band of Gosset (84) beneath the neurovascular bundle and

natatory ligaments to insert on the lateral digital sheet.

Layer three passes on each side of the flexor sheath to the

region of the MCP joint.

Natatory Ligaments

The natatory ligaments have transverse as well as curved fibers

that follow the contour of the webs. The curved or distal continuations of these fibers join the lateral digital sheet.

Lateral Digital Sheet

Gosset described these condensations of the superficial digital fascia on each side of the fingers (84). This structure

receives fibers from the natatory ligament, the spiral band,

and Grayson’s ligament.

Grayson’s and Cleland’s Ligaments (the Retaining Skin

Ligaments)

Both Cleland’s and Grayson’s ligaments stabilize the skin

during flexion and extension of the finger.

Grayson’s Ligaments. Grayson’s ligaments are palmar to

the neurovascular bundles and pass from the skin to the

flexor tendon sheath (77) (Fig. 10.52; see Fig. 10.51).

Grayson reported that they were found in pairs at each

interphalangeal joint and that only the proximal pair of ligaments about the DIP joint could be demonstrated with

certainty (92). Those of the PIP joint came in two pairs,

with the proximal pair arising from the flexor sheath at the

distal third of the proximal phalanx and the distal pair arising from the sheath over the proximal third of the middle

phalanx. Milford, in his comprehensive dissections of the

retaining ligaments of the digits, found that Grayson’s ligament was fragile and membranous and was strongest at the

middle three-fourths of the middle phalanx in the finger

and just proximal to the interphalangeal joint in the thumb.

Milford noted that the ligament originated from the palmar

aspect of the flexor tendon sheath and projected at right

angles (at variance with Grayson’s observation of an oblique

course) to the long axis of the finger. Milford concluded

that (a) Grayson’s ligament in the human probably is strong

enough to maintain the digital vessels and nerves in place

and prevent bowstringing when the finger is flexed; and (b)

clinically, Grayson’s and Cleland’s ligaments formed a tube

from the proximal aspect of the finger to the DIP joint,

where the digital nerves and vessels always can be found

during surgical dissection.

Cleland’s Ligaments. Cleland’s ligaments, based on Milford’s dissections, consist of four conelike structures that arise

598 Regional Anatomy

FIGURE 10.52. Grayson’s ligaments (fresh cadaver dissection).

The vertically oriented black suture is passing beneath Grayson’s

ligament, which is seen as a thin fascial partition in the middle

phalanx. (From Milford LW Jr. Retaining ligaments of the digits

of the hand: gross and microscopic anatomic study. Philadelphia:

WB Saunders, 1968:38, with permission.)

from the PIP joint on each side of the finger and the interphalangeal joint of the thumb (77,93) (Fig. 10.53; see Fig.

10.51). These ligaments are dense fibrous bundles that

diverge from their origin to insert into the skin. The fibers are

arranged in two planes and form a structure somewhat like a

cone. They are dorsal to the neurovascular bundle and are

arranged proximal and distal to the transverse retinacular ligament in the finger near its palmar insertion. The proximal

fibers are shorter than the distal fibers and are more perpendicular to the long axis of the phalanx. The largest bundle

originates from the lateral margin of the middle phalanx over

its proximal fourth, from the joint capsule of the PIP joint,

and from the flexor tendon sheath. These fibers are strong,

project in straight lines, and fan out to insert in an area of

skin larger than their origin, but all fibers insert proximal to

the DIP joint. The most dorsal of the fibers become taut

when the PIP joint is flexed (lending some stability to the

skin) because of stretching of the fibers over the condyle of

the proximal phalanx. The most palmar fibers become taut

with PIP joint extension, with similar stability noted in the

skin. The two distal bundles of this ligament originate from

the DIP joint from the bone and capsule, over a small, 1- to

2-mm area just proximal and distal to the joint. The strongest

bundle of Cleland’s ligament in the thumb (the proximal)

arises from the flexor tendon sheath just distal to the MCP

joint and then courses distally to insert into the adjacent skin.

The distal two bundles arise at the interphalangeal joint from

the bone and capsule over a small area (77).

Pulley System of the Wrist, Hand (Palm),

and Digits

Wrist

Kline and Moore in 1992 proposed that the TCL was an

important component of the finger flexor pulley system

(94). This broad and substantial ligament, which spans the

palmar side of the carpus, was sectioned in fresh-frozen

cadavers, and the authors noted a 25% increase in the

required excursion for the profundus and a 20% increase in

the superficialis. They noted that the increased excursion

that was consumed after release of the TCL resulted in less

remaining excursion for flexion of the other joints and thus

might contribute to weakness of grip noted after carpal tunnel release. They concluded that the main purpose of the

TCL was to act as a flexor pulley at the wrist. The increased

flexor tendon excursion, however, was demonstrated only

when the wrist was in the flexed position. This could result

in decreased grip strength when the wrist was flexed,

although most power gripping is done with the wrist in

extension. This study further serves to point out the importance of knowing the status of all three components of the

system—the wrist, palm, and finger—before performing

flexor tendon surgery throughout the system.

Palmar Aponeurosis Pulley

Manske and Lesker, in 1983, described the palmar aponeurosis pulley and noted its function as a pulley (90) (Fig.

10.54). This pulley is formed by the transverse fibers of the

palmar aponeurosis that are anchored on each side of the

flexor synovial sheath by vertical (sagittal) fibers or intertendinous septa, which attach to the deep transverse

metacarpal ligament and thus form an archway over the

flexor tendons. Its average width is 9.3 mm, and its proximal edge begins 1 to 3 mm distal to the beginning of the

flexor synovial sheath (91). Although it is not as closely

applied to the flexor tendons as the digital pulleys, closer

approximation may occur with increased tension on the

palmar aponeurosis, as in grasping. This proximal tension

may be provided by the palmaris longus or the FCU, or

both (91). Manske and Lesker established the functional

significance of this structure as a pulley by noting a signifi10.1 Palmar Hand 599

FIGURE 10.53. Cleland’s ligament (fresh cadaver

dissection). The arrow points to the largest bundle of

Cleland’s ligament, and the probe is beneath the second largest bundle. (From Milford LW Jr. Retaining

ligaments of the digits of the hand: gross and microscopic anatomic study. Philadelphia: WB Saunders,

1968:40, with permission.)

cant preservation of total range of finger motion if the palmar aponeurosis pulley was intact in conjunction with section of the critical A1 and A2 pulleys. Baseline total range

of motion was determined for each finger in 12 cadaver

hands, and the palmar aponeurosis and A1 and A2 pulleys

were sequentially cut in various orders. The results of these

studies indicated that functional loss associated with

absence of any one of the three proximal pulleys is minimal.

The loss of flexion associated with the absence of the A1 or

A2 pulley is insignificant as long as the palmar aponeurosis

pulley is present. The loss of flexion increases if the absence

of the A1 or A2 pulley is combined with absence of the palmar aponeurosis pulley. The authors concluded that as a

single functioning pulley, the A2 pulley was the most

important, followed closely by the A1 pulley. They noted

that although the position of the palmar aponeurosis pulley

was the least critical of the three, its importance as a pulley

was evident in the increased loss of flexion, from 5.7%

when it alone was present, to 12.6% when all three (palmar

aponeurosis, A1, and A2) pulleys were cut (90).

Digital Flexor Sheath

The digital flexor tendon sheath is composed of synovial

(membranous) and retinacular (pulley) tissue components

(Fig. 10.55). The membranous portion is a synovial tube

sealed at both ends. The retinacular (pulley) portion is a

series of transverse (the palmar aponeurosis pulley), annular, and cruciform fibrous tissue condensations, which

begin in the distal palm and end at the DIP joint. The floor

or dorsal aspect of this tunnel is composed of the transverse

metacarpal ligament, the palmar plates of the MCP, PIP,

and DIP joints, and the palmar surfaces of the proximal and

middle phalanges. In the index, long, and ring fingers, the

membranous portion of the sheath begins at the neck of the

metacarpals and continues distally to end at the DIP joint.

In most instances the small finger synovial sheath continues

proximally to the wrist (95–97). Visceral and parietal synovial layers are present (37,95,98–100). A prominent synovial pouch is present proximally and represents the confluence of the visceral and parietal layers. A visceral layer

reflection or pouch also is noted between the two flexors at

the neck of the metacarpal, but is 4 to 5 mm distal to the

more visible proximal and superficial portions of the synovial sheath. The membranous or synovial portions of the

sheath are most noticeable in the spaces between the pulleys, where they form plicae and pouches to accommodate

600 Regional Anatomy

FIGURE 10.54. The palmar aponeurosis pulley. This pulley is

formed by the transverse fibers of the palmar aponeurosis,

which are anchored on each side of the flexor synovial sheath by

vertical (sagittal) fibers or intertendinous septa, which attach to

the deep transverse metacarpal ligament and thus form an archway over the flexor tendons. Its average width is 9.3 mm, and its

proximal edge begins 1 to 3 mm distal to the beginning of the

flexor synovial sheath.

FIGURE 10.55. Digital flexor sheath. The digital flexor tendon sheath is composed of synovial

(membranous) and retinacular (pulley) tissue components. The membranous portion is a synovial

tube sealed at both ends. The retinacular (pulley) portion is a series of transverse (the palmar

aponeurosis pulley), annular, and cruciform fibrous tissue condensations, which begin in the distal palm and end at the distal interphalangeal (DIP) joint. The floor or dorsal aspect of this tunnel is composed of the palmar plates of the metacarpophalangeal, proximal interphalangeal, and

DIP joints, and the palmar surfaces of the proximal and middle phalanges.

flexion and extension. The retinacular (pulley) portion of

the sheath is characterized by fibrous tissue bands of annular and cruciform configuration that are interposed along

the synovial sheath in a segmental fashion and maintain the

flexor tendons in a constant relationship to the joint axis of

motion. The cruciform fibers are sometimes single oblique

limbs or “Y”-shaped (ypsiliform). Five annular and three

cruciform pulleys have been identified. The first of the five

annular pulleys begins in the region of the palmar plate of

the MCP joint. Most of these fibers (approximately twothirds) arise from the palmar plate; the remainder arise from

the proximal portion of the proximal phalanx. Although the

most usual configuration of the A1 pulley is that of a single

annular pulley, which averages 7.9 mm in width, it sometimes is represented by two or three annular bands. A distinct separation between the A1 and A2 pulleys is the usual

configuration. This separation ranges from 0.4 to 4.1 mm

and is widest on the palmar aspect. In those cases that do

not have a distinct separation between A1 and A2 pulleys,

there is a pronounced thinness to the retinacular tissue for

a distance of several millimeters at the usual site of separation, or large triangular openings laterally. This allows for

flexion at the MCP joint without any buckling of the pulley complex, and thus the potential for impingement of the

tendon is avoided. In contrast to the variability in configuration of the A1 pulley, the proximal edge of the A2 pulley

is constant in shape with somewhat oblique fibers of origin

beginning at the proximal and lateral base of the proximal

phalanx, which join annular fibers to make a prominent

and thick leading edge. Synovial outpouching is common

in the spaces between the pulleys. The A2 pulley is 16.8

mm in average width and is thickest in the distal end. The

deeper annular fibers of the A2 pulley are overlaid with

oblique fibers that at the distal end of A2 cross over each

other to form the first cruciate pulley. The third annular

(A3) pulley is located at the PIP joint and is firmly attached

to the palmar plate. The A3 pulley is present in most cases,

and the average width is 2.8 mm. The fourth annular (A4)

pulley is located in the mid-portion of the middle phalanx

and is overlaid with oblique fibers that cross over each other

to form a cruciate pulley, C3, at the distal end. The C3 pulley is not always a separate structure. The A4 pulley is 6.7

mm in average length and thickest in its middle aspect. The

fifth annular pulley is quite thin, 4.1 mm in average length,

and is attached to the underlying palmar plate at the DIP

joint. The membranous synovial sheath ends at the level of

the DIP joint, and no pulleys are present beyond the distal

joint (101).

Special Features of the Finger Flexor Sheath

Retinacular. Significant flexion of the finger is achieved

without buckling of the retinacular system or impingement

of the underlying tendons because (a) the broader pulleys,

A2 and A4, are located between joints, whereas the narrower pulleys, A1 and A3, are located over joints; (b) the

pulleys are arranged in a segmental fashion with synovial

pouches and windows between them; and (c) the thinner

and narrower cruciform pulleys are located near joints, and

their narrow palmar aspect can easily accommodate to the

confined space produced by acute flexion. The functional

adaptation of the retinacular system also is apparent in the

region of the MCP joint, where some form of anatomic

accommodation always is present between the A1 and A2

pulleys either in the form of definite separation of these two

pulleys, thinning of the contiguous margins of A1 and A2,

or triangular openings in the lateral margins of the retinaculum so that flexion can occur without buckling. Furthermore, compressibility of the various pulleys has been

reported and also may be a factor in accommodating joint

motion without buckling or impingement (102).

Membranous. Bunnell noted that a tendon sheath was an

adaptation that allowed a tendon to turn a corner. He

stated, “It glides around a curve on a thin film of synovial

fluid between two smooth synovial-lined surfaces, just as

metal surfaces in machinery glide on a thin film of oil.”

Bunnell further noted that a tendon sheath had two layers

of synovium, a visceral one investing the tendon and a parietal layer lining the fascial (retinacular) tunnel through

which the tendon glided (98). Lundborg et al. noted a well

vascularized membrane with plicae and pouches at the margin of the pulleys that was important for flexion and

stretching of the sheath (103). They were not able to

demonstrate any continuity of the synovial cell layer on the

friction surface of the A2 pulley, but they did note chondrocyte-like cells in the superficial layers of this pulley.

Knott and Schmidt also observed cartilage-like tissue at the

distal end of the A2 pulley (104). In certain avascular areas

of the palmar portion of the tendons, visceral synovial tissues were absent on histologic sections. Furthermore, in

some scattered areas of the palmar surface of the tendon,

there were areas with cartilaginous differentiation similar to

the findings in the A2 pulley. Lundborg et al. concluded

that the friction surface of the pulleys is devoid of vessels

and that friction and gliding in the digital sheath system

takes place between two avascular structures, namely, the

palmar aspect of the flexor tendons and the inner aspect of

the pulleys (103). These avascular gliding surfaces are nourished by diffusion from the synovial fluid. Histologic studies by Lundborg et al. demonstrated that the vascular plexus

of the synovial sheath is in continuity on the outside of the

rigid pulleys, and by this arrangement the pulleys can meet

the mechanical forces associated with finger flexion while

the synovial membrane avoids vascular compression, and

thus the microcirculation is not compromised (103). The

well vascularized synovial elements of the sheath represent a

dialyzing membrane that produces a plasma filtrate, the

synovial fluid, which acts as a lubricating agent and also as

a nutritional agent for the relatively avascular retinacular

system and tendon (103). The findings of Lundborg et al.

10.1 Palmar Hand 601

are appropriately compared with the findings of Cohen and

Kaplan, who in a study of the gross, microscopic, and electron microscopic (ultrastructure) structure of the flexor tendon sheath noted that the sheath consists of an uninterrupted layer of parietal synovium reinforced externally at

intervals by dense bands of collagen (the retinacular system)

(99). Cohen and Kaplan further noted that the contents of

the sheath were independently covered by a second similar

layer of visceral synovium, and that the two layers were continuous at the proximal cul-de-sac, the vincula origins, and

the tendon insertion (99). The synovial cells lining the pulley and covering the tendon were quantitatively, but not

morphologically, different from the synovial cells of the

membranous (synovial) portion of the sheath. The thickness of the synovial layers was greatest at the spaces between

the pulleys and thin or attenuated beneath the annular pulleys and on tendon surfaces distant from vincula and culde-sacs (99). Additional nutritional pathways were noted by

Weber, who identified nonvascular channels in the flexor

tendons of dogs and chickens (105). These channels were

mainly on the palmar surface, which is the least vascular.

The channels appeared to be associated with nonparallel

collagen fibers. Body fluid marked by fluorescein dye was

observed to penetrate the tendon in its least vascular area.

Motion of the flexor tendon augmented dye penetration

into the central portion of the tendon. Weber concluded

that his findings supported the concept that synovial fluid

nourished the flexor tendons in the digital theca (105).

Amis and Jones focused on the interior of the flexor tendon

sheath and noted that the inner aspect of the sheath was not

a continuous smooth surface (106). They noted that the

thin (membranous) parts of the sheath did not attach

directly to the proximal and distal borders of the pulleys in

continuity, but often overlapped the superficial edges of the

pulleys. Thus, on the inner aspect of the sheath, the pulleys

often stood apart from their surroundings, with free edges

pointing both proximally and distally. The significance of

these observations is that these free pulley edges may be sites

for impingement or triggering of a partially cut tendon, a

bulky or irregular tendon suture site, or a prominent suture

knot (106). Although the fibrous portions of the sheath

become contiguous near the end of the flexion arc, it is

obvious that impingement could occur about any free pulley edge during the act of flexion. This anatomic finding is

most noticeable about the distal end of the A2 pulley and

the proximal end of the A1 pulley (101).

Thumb

The flexor tendon sheath of the thumb, like the finger

sheath, contains membranous and retinacular components (Fig. 10.56). The thumb flexor sheath is a doublewalled tube sealed at both ends, and its synovial tissues are

similar to the finger sheath, with parietal and visceral layers. The thumb synovial sheath begins approximately 2

cm proximal to the radial styloid and ends just distal to

the interphalangeal joint. Three constant pulleys have

been identified: two annular and one oblique. The A1

pulley is located at the MCP joint. Its proximal two-thirds

arises from the palmar plate of the MCP joint and its distal one-third from the base of the proximal phalanx. It is

7 to 9 mm wide and 0.5 mm thick. The second pulley (the

oblique pulley) begins at the ulnar side of the base of the

proximal phalanx and continues in a distal and oblique

direction to end on the radial side of the proximal phalanx

near the interphalangeal joint. This oblique pulley is 9 to

11 mm wide at its mid-aspect and slightly wider at its

proximal and distal ends. It ranges from 0.5 to 0.75 mm

in thickness. The proximal end of the oblique pulley

appears to be closely associated with a part of the insertion

of the adductor pollicis tendon. The third pulley, the A2

pulley, is located near the insertion of the FPL and is centered over the palmar plate of the interphalangeal joint. It

is relatively thin (approximately 0.25 mm in thickness), 8

to 10 mm wide, and transversely oriented. The synovial

sheath ends 3 to 4 mm distal to this last pulley (107).

Functional Anatomy

The relative value of these pulleys has been evaluated by serial resections and subsequent measurement of joint motion,

as given in Table 10.10. Excision of the A1 pulley did not

result in significant change in joint motion with 2.5 cm of

FPL excursion. However, significant loss of interphalangeal

joint flexion did occur with release of the A1 and oblique

pulley, although the total arc of motion was nearly the

same. Absence of the oblique pulley resulted in only slight

loss of motion if the A1 and A2 pulleys were intact. The

oblique pulley is the most important pulley in the thumb

because the FPB can provide adequate and independent

MCP joint flexion, and the A1 pulley often is released for

stenosing tenosynovitis without apparent loss of function.

The A2 pulley appears to be of no great practical significance if the oblique pulley is intact (107).

Flexor Tendon Synovial Sheath Patterns

in the Hand

The preceding comments have focused on certain features

of the retinacular portion of the flexor tendon sheaths, but

it also is important to note the various patterns of the flexor

tendon synovial sheaths in the digits, palm, and wrist (see

Fig. 10.56).

Definitions

Radial Bursa

The radial bursa is the FPL synovial sheath that extends

from the region of the interphalangeal joint of the thumb

to 2.5 cm proximal to the wrist flexion crease (107).

602 Regional Anatomy

Ulnar Bursa

The ulnar bursa is the synovial sheath that surrounds the

FDS and FDP tendons in the palm and wrist. It begins

proximally at approximately the same level as the radial

bursa and continues distally to the region of the midpalm.

Synovial Sheath Patterns

Scheldrup, in a study of 367 hands using air inflation,

noted that in 85% there was a communication between the

radial and ulnar bursa. The tendon sheath of the small fin10.1 Palmar Hand 603

FIGURE 10.56. Composite view of the components of the synovial sheaths in the proximal fingers, thumb, palm, and wrist. In the index, long, and ring fingers, the membranous portion of

the sheath begins at the neck of the metacarpals and continues distally to end at the distal interphalangeal joint. In most instances, the small finger synovial sheath continues proximally to the

wrist. The radial bursa is the flexor pollicis longus synovial sheath, which extends from the region

of the interphalangeal joint of the thumb to 2.5 cm proximal to the wrist flexion crease. The

ulnar bursa is the synovial sheath that surrounds the flexor digitorum superficialis and profundus

tendons in the palm and wrist. It begins proximally at approximately the same level as the radial

bursa and continues distally to the region of the midpalm.

ger communicated with the ulnar bursa in 81%; the ring

finger in 3.5%; the middle finger in 4%; and the index finger in 5.2% (97). The most common arrangement of the

synovial sheaths of the fingers, thumb, palm, and wrist, as

well as the variations in descending order of frequency are

given in Figure 10.57.

Clinical Significance

These findings provide an anatomic basis or explanation for

the so-called horseshoe abscess and for other patterns of

infection in the hand.

Palmar and Wrist Spaces

In addition to the synovial-lined spaces in the hand that

may be involved by infection, there also are nonsynovial

actual and potential spaces that may be similarly involved.

Palmar Spaces

Historical Perspective

After noting that accumulations of pus in the palm often

were confined to the radial or ulnar side beneath the flexor

tendons, Kanavel named the most important spaces in the

palm the thenar and mid-palmar spaces (108). These were

potential spaces deep to the flexor tendons whose floor was

formed by the adductor fascia in the case of the thenar space

and the interosseous fascia in the case of the mid-palmar

space. Kanavel stated that these two spaces were separated

by a middle palmar septum that extended from the middle

finger metacarpal to the flexor tendons of the index finger

and thus formed a barrier between the two potential spaces.

According to Kanavel, these compartments represented

potential spaces into which infections might track (108).

Kaplan, however, noted that the central palmar compartment was divided only by an attachment of the ulnar bursa

to the third metacarpal bone (6). Kaplan further noted that

the thenar space was not located over the thenar eminence

but rather over the adductor muscle, and suggested that this

potential space should be called the adductor (or deep palmar radial) space. Similarly, he noted that the mid-palmar

space was not located over the midpalm, but over the ulnar

aspect of the palm, and thus could be called the palmar

ulnar space (6).

Current Perspective on the Central Palmar Spaces

Bojsen-Moller and Schmidt, in a study of the palmar

aponeurosis and the central spaces of the hand, reviewed the

previous work of Kanavel and Kaplan, who had noted the

presence of two palmar spaces (radial and ulnar), separated

by a middle palmar septum in the region of the third

metacarpal (88). Based on their study of 29 adult hands and

6 fetuses aged 5 to 6 months, Bojsen-Moller and Schmidt

described a central palmar space that was lined with loose

connective tissue and was bounded radially and ulnarly by

marginal septa that began as an extension of the side walls

of the carpal canal (Fig. 10.58). The floor was formed by

the palmar interosseous fascia, transverse metacarpal ligament, and adductor fascia, and the roof by the palmar

aponeurosis. The radial marginal septum extended distally

to the proximal phalanx of the index finger and formed the

radial wall of the lumbrical canal. This radial septum was

pierced by the FPL and the recurrent motor branch of the

median nerve, the branch from the radial artery to the

superficial palmar arch, and the vessels and nerves to the

thumb. The ulnar marginal septum was attached to the

shaft of the small finger metacarpal bone and distal to the

carpal canal was pierced by the digital branch of the ulnar

nerve and by the ulnar artery where it forms the superficial

palmar arch. Between these two marginal septa were seven

intermediate septa that, along with the marginal septa,

divided the distal aspect of the central space into four canals

to accommodate the flexor tendons and four canals to

accommodate the lumbricals and neurovascular bundles.

The seven intermediate septa were rectangular with a free

falciform proximal edge. They were attached to the underside of the longitudinal and transverse fibers of the palmar

aponeurosis and anchored deep in the hand to the transverse metacarpal ligament and interosseous fascia. Proximally, the intermediate septa extended into the acute angle

between the FDP and the lumbrical and were comparatively short or long to accommodate a distal or proximal

origin of the lumbrical. Thus, the central compartment was

a single space in the proximal palm and a series of small

compartments in the distal part. The middle palmar septum, previously described by Kanavel, was, in all probability, the vertical septum on the ulnar side of the index finger.

Based on the study of Bojsen-Moller and Schmidt, the central compartment is the entire space between the thenar and

604 Regional Anatomy

TABLE 10.10. THUMB JOINT FLEXION AT 2.5 CM

TENDON EXCURSIONa

Metacarpophalangeal Interphalangeal

Pulleys Intact (Degrees) (Degrees)

A1, OBL, A2 48 31

OBL, A2 49 31

A2 57 22

A1, A2 51 26

A1, first annular; A2, second annular; OBL, oblique.

aExcision of the A1 pulley did not result in significant change in

joint motion with 2.5 cm flexor pollicis longus excursion. However,

significant loss of interphalangeal joint flexion did occur with release

of the A1 and OBL pulley, although the total arc of motion was

nearly the same. Absence of the OBL pulley resulted in only slight

loss of motion if the A1 and A2 pulleys were intact. The OBL pulley is

the most important pulley in the thumb because the flexor pollicis

brevis can provide adequate and independent metacarpophalangeal

joint flexion, and the A1 pulley often is released for stenosing

tenosynovitis without apparent loss of function. The A2 pulley

appears to be of no great practical significance if the OBL pulley is

intact.

hypothenar eminences, and between the palmar aponeurosis and the deep palmar interosseous and adductor fascia,

and contains the flexor tendons and their synovial sheaths.

It is an actual and not a potential space (88).

Author’s Conclusions Regarding the Palmar Spaces

Knowledge of the synovial-lined spaces in the hand and fingers, along with the concept of potential palmar spaces, was

used by Kanavel to predict the likely pathways and localization of infection in the fingers and hand. Such knowledge

allowed the surgeon to detect and appropriately drain infections that might point to or present in characteristic locations. Based on the study of Bojsen-Moller and Schmidt, it

appears appropriate to accept the concept that the central

space or compartment of the hand as defined by these

authors is an actual space that encompasses the historical

palmar spaces of Kanavel (thenar and mid-palmar) and the

later modifications in terminology (adductor and deep palmar ulnar) advocated by Kaplan (6,108).

Wrist Space

The central compartment of the palm narrows proximally

toward the carpal canal and is connected through this canal to

a space in the palmar aspect of the wrist (88). The name

Parona has been associated most often with this non–synoviallined space on the flexor side of the wrist, which is located

between the flexor tendons and the pronator quadratus muscle and bounded radially by the FCR and ulnarly by the FCU

and antebrachial fascia (109). In 85% of the 367 hands in

10.1 Palmar Hand 605

FIGURE 10.57. Variations in the synovial sheath patterns in the fingers, thumb, palm, and wrist

[after Scheldrup (97)]. A: The most common pattern. B–H: Other patterns in descending order of

frequency.

606 Regional Anatomy

FIGURE 10.58. Central palmar space [after Bojsen-Moller and Schmidt (88)] and Parona’s space.

In addition to the synovial-lined spaces in the hand that may be involved by infection, there also

are nonsynovial, actual and potential spaces that may be similarly involved. Central palmar space:

This space is bounded radially and ulnarly by marginal septa that begin as an extension of the

side walls of the carpal canal. The radial marginal septum extends distally to the proximal phalanx of the index finger and forms the radial wall of the lumbrical canal. The radial septum is

pierced by the flexor pollicis longus and the recurrent motor branch of the median nerve, the

branch from the radial artery to the superficial palmar arch, and the vessels and nerves to the

thumb. The ulnar marginal septum is attached to the shaft of the small finger metacarpal bone,

and distal to the carpal canal is pierced by the digital branch of the ulnar nerve and by the ulnar

artery where it forms the superficial palmar arch. Between these two marginal septa are seven

intermediate septa that, along with the marginal septa, divide the distal aspect of the central

space into four canals to accommodate the flexor tendons and four canals to accommodate the

lumbricals and neurovascular bundles. These septa are attached to the underside of the longitudinal and transverse fibers of the palmar aponeurosis (PA) and anchored deep in the hand to the

transverse metacarpal ligament and interosseous fascia. Proximally, the intermediate septa

extend into the acute angle between the flexor digitorum profundus and the lumbrical and are

comparatively short or long to accommodate a distal or proximal origin of the lumbrical. Thus,

the central compartment is a single space in the proximal palm and a series of small compartments in the distal part. The central compartment is the entire space between the thenar and

hypothenar eminences, and between the PA and the deep palmar interosseous and adductor fascia, and contains the flexor tendons and their synovial sheaths. It is an actual and not a potential

space. Parona’s space: The name Parona has been associated most often with this non–synoviallined space on the flexor side of the wrist that is located between the flexor tendons and the

pronator quadratus muscle and bounded radially by the flexor carpi radialis and ulnarly by the

flexor carpi ulnaris and antebrachial fascia.

Scheldrup’s study, there was a natural connection between the

radial and ulnar bursa at the wrist. Parona’s space, located

between the radial and ulnar bursae, thus has the theoretical

potential to act as a conduit between these two structures and

produce the so-called horseshoe abscess (97).

Tendons

Nine extrinsic flexor tendons enter the hand through the

carpal tunnel, the FDS and the FDP to the four fingers, and

the FPL to the thumb (Fig. 10.59). The synovial sheaths

and retinacular constraints of these nine tendons have been

presented in the preceding section.

Flexor Pollicis Longus

The most radial of the nine flexors enters the flexor side of

the thumb between the two heads of the FPB and inserts on

the palmar base of the distal phalanx.

10.1 Palmar Hand 607

FIGURE 10.59. Flexor tendons. Nine extrinsic

flexor tendons enter the hand through the

carpal tunnel, the flexor digitorum superficialis

(FDS) and flexor digitorum profundus (FDP) to

the four fingers, and the flexor pollicis longus

(FPL) to the thumb. The FPL is the most radial of

the nine flexors and enters the flexor side of the

thumb between the two heads of the flexor pollicis brevis and inserts on the palmar base of the

distal phalanx. The FDP lie deep and side by side

in the carpal tunnel and insert on the palmar

base of the distal phalanges of the four fingers.

The FDS tendons are oriented “two-by-two”

(middle and ring are palmar to index and small)

in the carpal tunnel, lie superficial to the profundus tendons in the palm and proximal phalanx, and insert by a radial and ulnar division

into the palmar base of the middle phalanx. The

FDP passes through the FDS by a unique cleft or

division of the FDS that begins in the region of

the metacarpophalangeal joint. The first indication of division of the FDS is the appearance of a

shallow groove on its palmar surface, which subsequently develops into complete separation of

the tendon. Before this separation, the FDS

begins to form into a flat ellipse with a concave

underside, which, after division, “cups” the FDP

between its two sides. These two divisions of the

FDS, while “cupping” the FDP, begin progressively to separate and rotate outward on their

long axes so that in the region of the proximal

interphalangeal joint they are deep to the FDP,

have a broad, flat shape, and have rotated

almost 180 degrees on their long axis. The profundus tendon has thus passed through the FDS

and is now palmar to the FDS. The two divisions

of the FDS are rejoined for a distance of 1 to 2

cm by crossing over of some but not all of the

central fibers of the two divisions. This central

crossing over of these fibers forms a substantial

interdigitation known as Camper’s chiasma (see

Fig. 10.60). The FDS divisions then continue distally to insert on the lateral crest on each side of

the middle half of the palmar surface of the middle phalanx.

Flexor Digitorum Profundus

These four tendons, lying deep and side-by-side in the

carpal tunnel, traverse the palm to insert on the palmar base

of the distal phalanges of the four fingers.

Flexor Digitorum Superficialis

These four tendons, oriented “two-by-two” (middle and

ring palmar to index and small) in the carpal tunnel, lie

superficial to the profundus tendons in the palm and

proximal phalanx and insert by a radial and ulnar division

into the palmar base of the middle phalanx. The FDP

passes through the FDS by a unique cleft or division of

the FDS that begins in the region of the MCP joint. The

first indication of division of the FDS is the appearance

of a shallow groove on its palmar surface that subsequently develops into complete separation of the tendon.

Before this separation, the FDS begins to form into a flat

ellipse with a concave underside that, after division,

“cups” the FDP between its two sides. These two divisions of the FDS, while “cupping” the FDP, begin progressively to separate and rotate outward on their long

axes so that in the region of the PIP joint they are deep to

the FDP, have a broad, flat shape, and have rotated

almost 180 degrees on their long axis. The profundus tendon has thus passed through the FDS and is now palmar

to the FDS. The two divisions of the FDS are rejoined for

a distance of 1 to 2 cm by crossing over of some but not

all of the central fibers of the two divisions. This central

crossing over of these fibers forms a substantial interdigitation known as Camper’s chiasma (Fig. 10.60; see Fig.

10.59). The FDS divisions then continue distally to

insert on the lateral crest on each side of the middle half

of the palmar surface of the middle phalanx.

Vascular Supply of the Flexor Tendons in Their

Sheath

Terminology

The following terminology must be introduced at this time:

a vinculum (singular) is a specialized form of vascularized

mesotenon adapted to function in the confines of the flexor

tendon synovial sheath. The plural of vinculum is vincula.

A vinculum may be long and filamentous (thus the words

longum for singular and longa for plural) or short and

mesentery-like (breve for singular and brevia for plural).

Having explained this terminology, which often is encountered in descriptions of this unique vascular system, the

authors of this text propose to adopt and occasionally use

the following conventions when addressing these specialized forms of mesotenon. Both singular and plural forms

may be abbreviated along with the tendon they enter; thus,

the notation VBP could represent the singular or plural

form. It may be interpreted as vinculum breve profundus or

vincula brevia profundus, but means “a short, specialized

form of mesotenon that enters the profundus tendon.”

These abbreviations may be used occasionally, and it is

hoped that the adoption of this convention will aid the

reader in his or her understanding of this system.

Sources of Vascular Supply

In general, the vascular supply to the flexor tendons in the

synovial sheath is from (a) intrinsic longitudinal vessels in

continuation from the palm region; (b) synovial attachments to the enclosed flexor tendons in the proximal

sheath; and (c) specialized forms of mesotenon, the vincula,

located inside the sheath.

Intrinsic Longitudinal Vessels from the Palm. In the

palm, the flexor tendons are surrounded by very vascular

608 Regional Anatomy

FIGURE 10.60. Camper’s chiasma. Fresh

cadaver dissection of right middle finger

viewed from ulnopalmar aspect. The profundus tendon is retracted by a green rubber

band and the reflected third annular pulley

rests on a small green marker in the foreground.

connective tissue called paratenon. In the palm, proximal to

the sheath, the tendons are covered by an extensive vascular

plexus in a mainly longitudinal direction with multiple

anastomoses (103). After entrance into the sheath, this vascular pattern changes abruptly.

Proximal Synovial Sheath (Synovial Reflection) Vessels.

The proximal reflection of the synovial sheath is characterized by accordion-like synovial folds that allow longitudinal

movement without compromise of the circulation. Blood

vessels that originate from this area of the sheath form a well

defined vascular network on the surface of the tendons, but

end somewhat abruptly with numerous microvascular loops

approximately 1 cm from their origin. Distal to these loops,

the palmar aspect of the tendon surface appears to be more

or less avascular except for some small loops approaching

the surface from deeper aspects of the tendon, indicating

that there are internal vessels at this level.

Because of the differences in the vascular systems

between the FDS and FDP, these two tendons are discussed

separately.

Flexor Digitorum Superficialis Vascular Supply. In the

proximal part of the FDS there is a deep, well defined

intrinsic vascular pattern that ends at the base or mid-portion of the proximal phalanx, which corresponds to the

beginning of the commissure of the FDS. In this zone, there

is a short avascular segment (approximately 1 to 2 mm)

until the tendon is again vascularized with vessels from the

vinculum breve (VB) in the region of Camper’s chiasma.

Thus, the FDS has a proximal zone of vascular supply in the

form of intrinsic longitudinal vessels in continuation from

the palm and synovial attachments in the proximal sheath,

and a distal zone from the vinculum breve at Camper’s chiasma.

Flexor Digitorum Profundus Vascular Supply. The proximal zone vascular pattern from the longitudinal intrinsic

vessels from the palm and the synovial reflection continues

to the level of the FDS bifurcation, where many of these

vessels terminate in loop formations. The resultant avascular zone ends just distal to the FDS bifurcation, and the

FDP again demonstrates a vascular pattern (intermediate

zone) derived from a vinculum longum (VL) that sends

longitudinal branches proximally and distally on the dorsal

aspect of the tendon. These longitudinal vessels give off vertical loops that pierce deep into the tendon. The palmar or

friction surface of the tendon is devoid of vessels for a distance of approximately 1 mm, which represents one-fourth

to one-third of the thickness of the tendon. A few millimeters distal to the VL, there is a second zone of relative avascularity. The distal zone of vascular supply to the FDP is

represented by the VB at the distal tendon insertion and

consists mainly of longitudinal vessels with some vertical

loops.

Vincular Patterns in the Finger

Armenta and Lehrman, in a study of 116 cadaver fingers,

identified 4 groups of vincula that were based on their origin from what they considered to be 4 digital arterial arches

(110) (Fig. 10.61). Ochiai et al., in a study of 35 cadaver

hands, also identified 4 arterial transverse communicating

vessels that they believed played an important role in the

blood supply to the vincular system (111). These two studies are at variance, in terms of number and location, with

those of Strauch and de Moura, who identified only three

arches (37). Armenta and Lehrman noted that the first and

second arches and their respective vincula were the primary

carriers of circulation to the FDS, and the third and fourth

were the primary carriers to the FDP (110). Disregarding

for the moment the number and location of the digital arterial arches, it is apparent that the vincula receive their circulation from transverse communicating branches of the

digital artery, originating in a sequential fashion from the

region of the base of the proximal phalanx, the neck of the

proximal phalanx, the base of the middle phalanx, and the

neck of the middle phalanx. These four branches, from

proximal to distal, are called the branch to the vinculum

longum, proximal transverse digital artery, interphalangeal

transverse digital artery, and distal transverse digital artery

(111). The convention adopted by Armenta and Lehrman

was to name the vinculum according to its source; thus, the

vinculum from the most proximal of the transverse vessels

was V-1, and the vinculum from the distal transverse digital arch was V-4. Another convention, as published by

Lundborg et al. and Ochiai et al., was to note that, in general, the superficialis and profundus had both a VL and VB

(103,111). It must be appreciated that these vincula are not

visible if the sheath is intact. Both Ochiai et al. and

Armenta and Lehrman noted variations in size, shape, incidence, and position of origin (radial or ulnar) (110,111).

The following variations and arrangements of the vincula as

described by Ochiai et al. in their study of 35 hands are

noteworthy: (a) the VB was consistently found in all fingers; and (b) the VL was found to vary in type, incidence,

and location, with three types of distribution of the VL

superficialis (VLS) and five types of distribution of the VL

profundus (VLP). The VLS arose from the radial or ulnar

side (approximately equally distributed, but 37 fingers had

both radial and ulnar types) of the base of the proximal phalanx and attached to one or two slips of the superficialis tendon just proximal to the decussation, and received its blood

supply from the transverse communicating artery (the VLS

artery) at the base of the proximal phalanx. The VLS was

absent in 35 of 130 fingers (27%), usually in the long and

ring fingers. The five types of distribution of the VLP were

distal, middle, mixed, proximal, and absent. The most common (100 of 130 fingers) type was the middle, which was

characterized by a VLP that came between the two FDS

slips distal to Camper’s chiasma and entered the underside

of the FDP. Its vessel of origin was the proximal transverse

10.1 Palmar Hand 609

610 Regional Anatomy

FIGURE 10.61. Vascular supply of the flexor tendons in their sheath: the vincular system. A: A

vinculum may be long and filamentous (longum for singular and longa for plural) or short and

mesentery-like (breve for singular and brevia for plural). Each flexor tendon usually has a long

and short form of this specialized mesentery-like structure. VBP and VLP, the short and long vinculum to the profundus tendon; VBS and VLS, the short and long vinculum to the superficialis.

See text for discussion of the two other sources of intrinsic blood supply to the tendons by intrinsic longitudinal vessels from the palm and proximal synovial sheath vessels. The vincula receive

their circulation from transverse communicating branches of the digital artery called the branch

to the vinculum longum, proximal transverse digital artery, interphalangeal transverse digital

artery, and distal transverse digital artery. B: Fresh cadaver dissection of right middle finger as

viewed from the ulnar side. The green rubber band is looped around the profundus tendon and

the reflected third annular (A3) pulley rests on a green marker; the jeweler’s forceps is reflecting

the flexor digitorum superficialis to show the VBS, and behind the tip of the forceps is the VLP.

Note also the VBP to the left (distal) adjacent to the A4 pulley, and the VLS proximally adjacent

to the cleft between the A1 and A2 pulleys.

A

B

artery. Based on the observations of Ochiai et al., this middle type of VLP appears to represent a drastically modified

continuation of the VBS. The second most common (48 of

130 fingers) type of VLP was the proximal, in which the

VLP appeared to be a continuation of the VLS and entered

the underside of the FDP just proximal to Camper’s chiasma. The reader is referred to the classic article by Ochiai

et al. for details (111).

Thumb Vinculum

Armenta and Fisher, in a study of 76 cadaver thumbs,

found that approximately 90% had a VB (112). This vinculum had the shape of a truncated cone, was located in the

distal third of the proximal phalanx, continued over the palmar plate of the DIP joint, and extended over a distance of

approximately 20 mm in the phalanx. Its insertion on the

underside of the FPL was approximately 18 mm wide (see

Fig. 10.27). The authors cut the FPL at the interphalangeal

joint but distal to the vincula, and noted that incomplete

flexion of the interphalangeal joint was possible because of

the attachment of the VB to the palmar plate. Clinically, the

flexion force generated by this vincular attachment is less

than normal, and such an arrangement can be detected by

opposing the flexion force and noting its decreased magnitude. The authors noted that a laceration of the FPL within

the range of 25.6 ± 6.3 mm proximal to the interphalangeal

joint could leave the FPL tethered at the laceration site

because of the vinculum attachment.

Clinical Significance of the Vascular Supply and the

Vincular System of the Flexor Tendons in the Sheath

Recent advances in the intraoperative and postoperative

management of flexor tendon injuries and a better understanding of tendon nutrition and the repair process may

be correlated with our knowledge of the vascular supply of

the flexor tendons in the sheath. The comparative role of

synovial nutrition and the vascular supply in tendon healing will not be debated here except to put into context the

value of avoiding damage to the vascularity of the tendons

in the sheath. This is illustrated by the following clinical

examples:

1. Removal of the FDS for a tendon transfer is best performed proximal to or at the proximal edge of Camper’s

chiasma to preserve the VBS and the VLP. This may

have the incidental side benefit of avoiding the potential

for hyperextension deformity at the PIP joint in addition to the preservation of blood supply to the FDS and

FDP.

2. Core intratendinous sutures are placed in the relatively

avascular palmar aspect of the profundus tendon when

practical.

10.1 Palmar Hand 611

FIGURE 10.61. (continued) C: Latex injection of right middle finger viewed from ulnar aspect

showing proximal transverse digital arch at the neck of the proximal phalanx (blue triangular

pointer), check-rein ligament (green marker), reflected A2 pulley, VBS, and VLP.

C

3. The vincula may help to tether lacerated flexor tendons

near their site of injury, but this also may give a falsenegative result when testing for tendon function. It has

been suggested that the VBS at the PIP joint and the

VBP at the DIP joint may play an accessory role in flexion because of their attachment to the palmar plate

(113), and this matches the observations of Armenta

and Fisher regarding the VB of the thumb (112).

Finally, the FPL has a synovial sheath that is longer than

the finger synovial sheath, but has only one mesotenon, the

VB, at its distal insertion (112).

SURGICAL EXPOSURES

General Principles

Elective Incisions in the Palm and Digits

Improperly placed incisions in the hand, especially in the

palm and flexor aspect of the fingers and thumb, have a

great potential not only for being cosmetically unacceptable

but also for producing thick, heavy scars that may limit

function. Incisions that cross palmar or digital flexion

creases at right angles uniformly result in a scar that limits

function. Incisions that parallel these creases or cross at

oblique angles are less likely to result in unfavorable scars.

In general, skin incisions should be centered over the operative site, but if moving the incision a few millimeters

would improve the cosmetic result, this should be considered. Skin incisions may be placed in skin creases as long as

invagination of the skin is avoided during closure. Skin

flaps should be as thick as possible, have broad bases, undermined only to the extent required, and handled gently,

especially at their tips.

Structures at Risk

Many important structures in the hand are immediately

beneath the skin. Four such structures are the proper sensory nerves to the radial side of the index finger and the

612 Regional Anatomy

FIGURE 10.62. Four nerves at risk.

Fresh cadaver dissection showing

three sensory and one motor nerve

(green triangles) at risk during incisions in their region. These nerves are

the proper sensory nerves to the

ulnar side of the small finger and the

radial side of the index finger, the

radial digital nerve of the thumb

adjacent to the first annular pulley,

and the recurrent motor branch of

the median nerve at the base of the

thenar eminence. The small and

index finger nerves are at risk with

transverse incisions in the distal

aspect of the palm, the radial sensory

nerve of the thumb with trigger

thumb release, and the motor branch

of the median with any incision

about the base of the thenar eminence. The sensory nerves are especially vulnerable because during

surgery the hand is made flat and the

digits extended by static holding

devices or by the surgeon’s assistant.

This brings these structures nearer to

the surface by compressing or flattening the subdermal fat or areolar

tissues, placing them under increased

tension and making them more

liable to injury.

ulnar side of the small finger; the recurrent motor branch of

the median nerve at the base of the thenar eminence; and

the radial digital nerve of the thumb adjacent to the A1 pulley (Fig. 10.62). The index and small finger nerves are at

risk with transverse incisions in the distal aspect of the

palm. The motor branch is at risk with any incision about

the base of the thenar eminence, and the radial sensory

nerve of the thumb is at risk with trigger thumb release.

The sensory nerves are especially vulnerable because the

hand is made flat and the digits extended by static holding

devices or by the surgeon’s assistant. This brings these structures nearer to the surface by compressing or flattening the

subdermal fat or areolar tissues, places them under

increased tension, and makes them more liable to injury.

The vulnerability of these nerves reminds us that dissection

in the hand must proceed layer by layer with concurrent

identification of vital structures.

Indications

Surgical incisions in the palm and digits may be required

for the management of tumors, aneurysms, Dupuytren’s

disease, flexor tendon or blood vessel lacerations, tendon

grafts, sheath infections, stenosing flexor tenosynovitis, harvesting of full-thickness skin grafts, nerve injuries, and joint

dislocations.

Landmarks

Useful landmarks include the thenar and hypothenar eminences, the thenar, proximal, and distal palmar creases, and

the proximal, middle, and distal digital flexion creases.

Patient Position

In general, the upper extremity is positioned on a well

padded arm table with the forearm in supination. The

required position of the upper extremity usually is evident

and is presented as required.

Elective Incisions in the Palm, Fingers,

and Thumb

Vertical

Although incisions in the palm often are transverse, they

may be vertical if they do not cross a flexion crease (Fig.

10.63). Such vertical incisions are most useful in the distal

palm for stenosing tenosynovitis of the flexor tendons of the

fingers.

The Zig-Zag

The zig-zag incision, initially designed for use in the

flexor aspect of the finger, is a useful incision in the palm

(114) (Fig. 10.64). This incision allows crossing of the

palmar creases at oblique angles and can provide a comprehensive exposure when needed. Ideally, the points or

tips of the skin flaps should form an angle of 90 degrees

or more.

Technique

The components of the incision are carried from the flexion creases, alternating from one side to the other of the

finger. The incision may be easily adapted to accommodate an oblique or transversely oriented traumatic incision. The zig-zag incision also is suitable for the thumb.

This incision provides not only excellent exposure of the

flexor sheath, but access to both neurovascular bundles,

which may require repair concurrent with the flexor tendon. Although the mid-axial incision has the theoretic

advantage of placing the scar on the nontactile area of the

finger or thumb, the palmar zig-zag incision has not produced any problems of this sort in our experience. Precautions in using the zig-zag incision include carrying the

points of the triangles to the mid-axial line and recognizing that the neurovascular bundle lies beneath the point

of the skin triangle.

10.1 Palmar Hand 613

FIGURE 10.63. Vertical palmar incisions. Although incisions in

the palm often are transverse, they may be vertical if they do not

cross a flexion crease. Such vertical incisions are most useful in

the distal palm for stenosing tenosynovitis of the flexor tendons.

Mid-Axial Incision

This incision was advocated by Bunnell and was used by

him for primary tendon repair and flexor tendon grafts (98)

(Fig. 10.65). It was used extensively by Boyes and Stark for

flexor tendon grafts (115).

The mid-axial incision centered over the respective joint

also may be used to expose the PIP and DIP joints.

Technique

The position of the mid-axial incision may be determined

by flexing the finger and drawing a line that joins the dorsal aspects of the flexion creases. This line represents the

zone of minimum skin tension, results in the least amount

of scar formation, and avoids contracture. Exposure is facilitated by placing the incision on the radial side of the index,

long, and ring fingers and the ulnar side of the small finger.

The neurovascular bundle is contained in the palmar aspect

of the flap. The dorsal sensory branch of the digital nerve in

the proximal phalanx crosses over the incision and may be

at risk in this incision, and should be looked for and preserved.

Skin Incisions for the Management of

Lacerations in the Palm and Fingers

Lacerations in the palm or fingers may require innovative

extensions to yield adequate exposure and at the same time

preserve the blood supply of the skin flaps and avoid scar

contracture (Fig. 10.66). Some lacerations are situated across

614 Regional Anatomy

FIGURE 10.64. The zig-zag incision. The zig-zag incision, initially designed for use in the flexor aspect of the finger, also is

useful in the palm. This incision allows crossing of the palmar

creases at oblique angles and can provide a comprehensive

exposure when needed. Ideally, the points or tips of the skin

flaps should subtend an angle of 90 degrees or more.

FIGURE 10.65. The mid-axial incision. A: The position of the mid-axial

incision may be determined by flexing the finger and drawing a line that

joins the dorsal aspects of the flexion

creases. B: Exposure is facilitated by

placing the incision on the radial side

of the index, long, and ring fingers

and the ulnar side of the small finger.

The neurovascular bundle is contained in the palmar aspect of the

flap. The dorsal sensory branch of the

digital nerve in the proximal phalanx

crosses over the incision and may be

at risk in this incision, and should be

looked for and preserved.

A

B

flexion creases, and surgical extensions of these wounds must

be designed to minimize the adverse effects of the original

wound. Primary revision by a Z-plasty may be indicated if it

can be performed without compromise to the circulation of

the skin flaps. If primary resolution of an adverse laceration

cannot be achieved at the time of initial surgery, the laceration may be closed and the scar dealt with at a later date.

Extensions of lacerations may be achieved as required by

applying the principles of the mid-axial incision, the Bruner

zig-zag, or a combination of these incisions.

The method of extension may be guided by the preoperative evaluation and the anticipated requirements of the

exposure. In general, the flaps should be broad based, kept

as thick as possible, and handled gently.

Joints

Thumb Metacarpophalangeal Joint, Ulnar

Aspect

Indications

This exposure is useful for reconstruction or reattachment

of the UCL or for fractures of the MCP joint area.

Landmarks

A useful landmark is the dorsal bony prominence of the

thumb metacarpal at the MCP joint.

Incision

A gently curved dorsal radial incision, approximately 3 to 4

cm long with the apex of the curve situated toward the

thumb web, is centered over the MCP joint (Fig. 10.67A).

Sensory branches of the radial nerve should be identified

and preserved.

Technique

The UCL of the thumb MCP joint is covered by and virtually hidden by the extensor hood (see Fig. 10.67B–E). It

is necessary to reflect this hood to gain appropriate exposure

of this area. Although partial exposure may be obtained by

separating the hood in the direction of its fibers, a more

comprehensive exposure that might be required for reconstruction of the collateral ligament by graft may be achieved

by reflecting the extensor hood. The adductor pollicis

inserts into the extensor hood, the base of the proximal phalanx, and the palmar plate. Reflection of the hood and its

specific adductor insertion exposes the ulnar side of the

MCP joint, including the UCL and the bone insertion of

the adductor that is just distal to the attachment of the

UCL into the proximal phalanx. The dorsal skin flap is elevated to expose the EPL over the MCP joint. Beginning at

the proximal margin of the hood, a 1-mm-wide portion of

the EPL is dissected free with a scalpel in the direction of its

fibers for a distance of approximately 3 cm. The hood

10.1 Palmar Hand 615

FIGURE 10.66. A, B: Skin incisions for the management of lacerations in the palm and fingers.

Lacerations in the palm or fingers may require innovative extensions to yield adequate exposure

and at the same time preserve the blood supply of the skin flaps and avoid scar contracture. Some

suggestions for extension of these lacerations are depicted. Extensions of lacerations may be

achieved as required by applying the principles of the mid-axial incision, the Bruner zig-zag, or a

combination of these incisions. The method of extension may be guided by the preoperative

evaluation and the anticipated requirements of the exposure. In general, the flaps should be

broad based, kept as thick as possible, and handled gently.

mechanism then may be retracted away from the UCL to

expose its entire length. The UCL may be avulsed proximally or distally, and if avulsed distally may carry with it a

fragment of bone. This exposure allows complete evaluation

of the ligament and reattachment by a technique of the surgeon’s choice. Secondary reconstruction by free tendon

graft or capsular and adductor insertion advancement also

may be accomplished through this approach. The 1-mm

margin of the EPL is reattached to its site of origin, which

maintains the normal anatomic arrangement and balance of

the hood mechanism.

Thumb Metacarpophalangeal Joint, Radial

Aspect

Incision

A gently curved dorsal radial incision, approximately 3 to 4

cm long, with the apex of the curve situated toward the

616 Regional Anatomy

FIGURE 10.67. Surgical approach to the

ulnar aspect of the metacarpophalangeal

joint of the thumb. A: Dorsal ulnar incision. B, C: Incision and reflection of the

hood to expose the ulnar collateral ligament (UCL). D: Fresh cadaver dissection of

the right thumb showing the extensor

hood and adductor expansion, the incision into the hood, and the extensor pollicis longus.

A B,C

D

radial side of the thumb, is centered over the MCP joint

(Fig. 10.68A). Sensory branches of the radial nerve should

be identified and preserved.

Technique

The dorsal skin flap is elevated to expose the confluence of

the EPB and EPL over the MCP joint (see Fig. 10.68B–E).

Beginning at the proximal margin of the hood on its radial

side, a 1-mm-wide portion of the EPL is dissected free with

a scalpel in the direction of its fibers for a distance of

approximately 3 cm. Careful incision into the hood and

development of a narrow band of the EPL over the MCP

joint preserves the insertion of the EPB on the proximodorsal aspect of the proximal phalanx. The lateral portion of the APB inserts into the extensor hood and the

medial portion into the base of the proximal phalanx.

Reflection of the hood and its specific portion of the APB

exposes the RCL and the proximal phalangeal attachments

of the medial portion of the APB and the FPB. These insertions are distal to the RCL attachment and may be detached

and reflected as required. Repair or reconstruction is performed, followed by careful reapproximation of the hood.

Finger Metacarpophalangeal Joint (Mid-Axial,

Radial Aspect of Index)

Indications

This radial mid-axial approach may be used to repair a disrupted RCL.

Incision

A gently curved, 3-cm incision is made over the radial

aspect of the index finger (Fig. 10.69A). Sensory branches

of the radial nerve are identified and preserved.

Technique

The skin flaps are developed and the underlying hood and

sagittal band identified (see Fig. 10.69B and C). Beginning

at the proximal edge of the sagittal band, a 1-mm-wide, 3-

cm-long strip of the extensor tendon is developed by sharp

dissection. The distal aspect of the hood is incised in the

direction of its fibers to release this flap distally. This

detached segment of the hood is then reflected to expose

the bony insertion of the first DI muscle and the RCL. Portions of the insertion of the first DI may be reflected as

required and later reattached.

Proximal Interphalangeal Joint, Palmar

Indications

This incision is designed for approaches to the palmar

aspect of the PIP joint and may be used for palmar plate

arthroplasty or capsulectomy of the PIP joint that is contracted in flexion.

Incision

The incision represents the central portion of the Bruner

incision and its apex is centered over the ulnar side of the

PIP joint flexion crease (116).

Technique

After elevation of this broad-based triangular flap, the flexor

sheath between the A2 and A4 pulleys is excised and the

flexor tendons retracted for exposure of the palmar plate

and check-rein ligaments. The VB to the FDS and the proximal transverse digital arteries near the proximal edge of the

palmar plate are preserved, if possible.

10.1 Palmar Hand 617

FIGURE 10.67. (continued) E: Reflection of

E the hood to expose the UCL.

FIGURE 10.68. Surgical approach to the

radial aspect of the metacarpophalangeal

(MCP) joint of the thumb. A: Dorsal radial

incision. B, C: Incision and reflection of the

hood to expose the radial collateral ligament (RCL). D: Fresh cadaver dissection of

the radial side of the MCP joint of the right

thumb showing the extensor hood and

abductor expansion, the incision into the

hood, and abductor expansion. E: Reflection of the hood reveals the underlying

RCL. Portions of the capsule have been

removed for clarity.

A B,C

D

E

Proximal Interphalangeal Joint, Mid-Axial

This approach represents a portion of the finger mid-axial

incision and is used to approach the PIP joint for fractures,

fracture dislocations, or collateral ligament injuries. After

incision of the skin, the underlying transverse retinacular

ligament is identified and incised, which allows undermining and dorsal retraction of the extensor mechanism and

exposure of the lateral aspect of the joint.

CLINICAL CORRELATIONS

Dupuytren’s Contracture

Dupuytren’s contracture, a disease of the palmar and digital

fascia, has an unknown etiology, and the focus of this presentation is on the changes that may occur in and about the

palmar and digital fascia. These normal tissues appear to

become diseased in response to increased tension. The normal anatomy of the palmar and digital fascia has been presented in the section on the retinacular system of the hand.

Terminology

This text uses the term bands for normal fascia and cords for

diseased fascia, as originally suggested by Luck (117) and

used by others (85,118) (Fig. 10.70A). The palmar fascia is

defined as the specialized fascial structure in the central portion of the palm with longitudinal, transverse, and vertical

fibers. The longitudinal fibers represent the distal continuation of the palmaris longus (when present). These fibers

begin as a conjoined apex at the base of the palm and form

bundles in the middle and distal palm that course to the

10.1 Palmar Hand 619

FIGURE 10.69. Surgical approach to the radial collateral ligament (RCL) of the index finger. A: A gently

curved, 3-cm-long incision is made over the radial

aspect of the index finger. Sensory branches of the

radial nerve are identified and preserved. B, C: The

skin flaps are developed and the underlying hood

and sagittal band identified. Beginning at the proximal edge of the sagittal band, a 1-mm-wide, 3-cmlong strip of the extensor tendon is developed by

sharp dissection. The distal aspect of the hood is

incised in the direction of its fibers to release the flap

distally. This detached segment of the hood is then

reflected to expose the bony insertion of the first dorsal interosseous (DI) muscle and the RCL. Portions of

the insertion of the first DI may be reflected as

required and later reattached. After the RCL is

repaired, the reflected hood is reattached to maintain balance in the extensor mechanism.

A

B

C

corresponding four fingers and in some instances to the

thumb. The longitudinal fibers are more or less parallel to

the deeper flexor tendons, and because of this arrangement

are sometimes called pretendinous bands. The four bundles

of longitudinally oriented fibers overlay transverse fibers in

the palm that are located at the junction of the middle and

distal thirds of the palm and over the MCP joints.

McGrouther has noted that these longitudinal fibers divide

into three layers in the distal palm (85). Layer one, the most

superficial, inserts into the skin of the distal palm and onto

the proximal aspect of the flexor sheath. Layer two splits

and passes on each side of the flexor sheath, where it continues distally as the spiral band of Gosset (84) beneath the

neurovascular bundle and natatory ligaments to insert on

the lateral digital sheet. Layer three passes on each side of

the flexor sheath to the region of the MCP joint (85).

Clinical Significance

Recognition of the distinct anatomic separation of the longitudinal (involved) and transverse (noninvolved) fibers of the

palmar fascia and the distal separation of the longitudinal

fibers into three layers allows the surgeon selectively to excise

the diseased tissue, in contrast to excision of all fascial tissue

and preservation of the neurovascular bundles (85,119).

Pretendinous Bands

The pretendinous bands of the palmar fascia are the most

common site for presentation of Dupuytren’s contracture. A

palpable nodule may progress to a prominent pretendinous

cord, which may produce a flexion contracture of the MCP

joint. Although the pretendinous cord is the primary cause of

flexion contracture of the MCP joint, it may join the central

cord of the finger that extends well beyond the PIP joint. The

origin of the central cord is from the superficial fibrofatty digital fascia on the flexor side of the finger. The central cord

always is in continuity with the pretendinous cord (118).

Transverse Fibers

Only the longitudinal fibers (pretendinous bands) of the

palmar fascia are involved, and the transverse fibers ideally

are left behind during excision of the diseased palmar fascia.

(85,119). However, the transverse fibers to the thumb web,

the PCL, and DCL, which are more obliquely oriented and

subject to tension, may contract and be responsible for loss

of abduction and extension of the thumb.

Natatory Ligament

The natatory ligaments frequently are diseased, and because

this ligament not only spans the finger web space but also

sends fibers distally into the fingers, it may be responsible

for web space contracture as well as PIP joint contracture.

Pathologic Anatomy of the Finger Fascia

The fibers in the finger that may become diseased are (a)

the fibrofatty fascia on the flexor aspect of the fingers; (b)

the distal continuation of the pretendinous fibers, called the

spiral band; (c) the distal (longitudinal) extension of the

natatory ligaments; (d) Grayson’s ligament (as terminal

620 Regional Anatomy

FIGURE 10.70. Normal and pathologic anatomy of the palmar

and digital fascia. A: Normal components of the palmar and digital fascia.

A

attachment for the spiral bands); and (e) the lateral digital

sheet (84) (see Fig. 10.70B and C).

Fibrofatty Fascia

This tissue forms the central cord in the finger and joins the

pretendinous cord of the palm to form a continuous cord

from the palm to the middle phalanx. It often divides into

two tails that attach to the flexor sheath and osseous middle

phalanx.

Spiral Band

These fibers (McGrouther’s layer two) are the deep and distal continuation of the pretendinous band on each side of

the flexor sheath. They pass deep to the neurovascular structures as they proceed to the lateral side of the finger, and

then migrate superficial to the neurovascular bundle to

attach to the middle phalanx by means of Grayson’s ligament (85). This configuration progressively displaces the

neurovascular bundle with increasing PIP joint contracture,

10.1 Palmar Hand 621

FIGURE 10.70. (continued) B, C: Changes in the palmar and digital fascia that may be seen in

Dupuytren’s disease.

B C

first toward the midline, then proximally, and then superficially. This places the neurovascular bundle at considerable

risk during surgery because the neurovascular bundle spirals

around this fascial structure, called the spiral cord. The spiral cord is either a continuation of the spiral band or arises

from the musculotendinous junction of an intrinsic muscle;

it attaches distally to the flexor sheath and bone in the middle phalanx.

Natatory Ligament

Disease and contracture of the transverse elements of the

natatory ligaments form the natatory cords that produce

contracture of the finger web spaces, with loss of abduction

of the fingers. The distal digital extension of the natatory

ligament joins the spiral band, and these two bands subsequently join the lateral digital sheet to form the lateral cord.

Grayson’s Ligament

Grayson’s ligaments, located in the middle and proximal

phalanges, pass from the digital flexor sheath, palmar to the

neurovascular bundle, to the lateral digital sheet and are in

the same fascial plane as the natatory ligaments (84,118).

Grayson’s ligaments provide attachment for the spiral cords

to the middle phalanx (85,118).

Lateral Digital Sheet

The lateral digital sheet, named by Gosset, is a condensation of the superficial fascia on either side of the finger (84).

It receives fibers from the natatory and spiral ligaments as

well as from Grayson’s and Cleland’s ligaments (84,118).

When diseased, it is known as the lateral cord (118).

Lateral Cord

The lateral cord runs from the natatory ligament to the lateral digital sheet. It usually does not cause PIP joint contracture except on the ulnar side of the small finger, where

it attaches to an abductor cord overlying the ADM and can

cause PIP joint contracture.

Retrovascular Cord

This cord lies deep to the neurovascular bundle and arises

from the periosteum of the lateral base of the proximal phalanx, passes close to the PIP joint, and ends at the lateral

aspect of the distal phalanx. It is the usual cause of DIP

joint contracture and an occasional cause of PIP joint contracture (85,118).

Isolated Digital Cord

Isolated cords may arise in the fingers as single or double

cords without any attachments in the palm. These cords

arise from the periosteum at the base of the proximal phalanx in conjunction with adjacent ligaments. They pass distally to displace and then cross the neurovascular bundle,

inserting on the tendon sheath or bone of the middle phalanx. These cords may result in a significant loss of extension of the PIP joint and cause isolated contractures (120).

Table 10.11 summarizes the relationship between fascial

bands/ligaments, cords, and the clinical result of cord formation.

First Web Space Pathologic Anatomy

Although only the longitudinal fibers (pretendinous bands)

of the palmar fascia are involved in the hand, the transverse

fibers to the thumb web, PCL, and DCL are more obliquely

oriented and are subject to tension (Fig. 10.71). If diseased,

they may contract and be responsible for loss of abduction

and extension of the thumb (85).

Trigger Digits (in the Adult)

Definition

Wolfe has observed that tendovaginitis may be a more accurate term than tenosynovitis to describe the inflamed and

thickened retinacular sheath that characterizes so-called

trigger digits and trigger thumb (121). This condition

results in painful catching or triggering of the involved

622 Regional Anatomy

TABLE 10.11. DUPUYTREN’S DISEASE: FASCIAL BANDS THAT MAY FORM CONTRACTURE CORDS

Fascial Bands/Ligaments Cords Result

Palm Pretendinous bands of palmar fascia Pretendinous cord Metacarpophalangeal joint contracture

Commissure Natatory ligaments Natatory cords Digital web contracture

Proximal commissure ligament First commissure cords Thumb web contracture

Distal commissure ligament First commissure cords Thumb web contracture

Finger Spiral band Spiral cord Displaces neurovascular bundle, PIP joint

contracture

Fibrofatty fascia Central cord PIP joint contracture

Natatory ligament and lateral digital sheet Lateral cord PIP joint contracture V (see text)

Periosteum of proximal phalanx Retrovascular cord Distal interphalangeal contracture

Periosteum of proximal phalanx Isolated digital cord PIP contracture

PIP, proximal interphalangeal.

flexor tendon as the patient flexes and extends the digit.

The digit may often catch or lock to the extent that passive

manipulation may be required to unlock or extend the

digit.

Pathologic Anatomy

This condition is due to impingement of the flexor tendon

at the level of the A1 pulley, with changes in the pulley that

include thickening and microscopic signs of degeneration.

Comparison of the ultrastructure of normal and trigger A1

pulleys revealed chondrocytes in the friction layer of the

normal pulley and chondrocyte proliferation and the presence of type III collagen in the abnormal pulleys (122).

These authors proposed that the contact surfaces of the pulley and flexor tendon developed fibrocartilaginous metaplasia owing to repetitive compressive loads (122).

Treatment

Conservative treatment is by steroid injection into the

flexor sheath. Surgical treatment is by release of the A1 pulley. Both transverse and longitudinal incisions may be used

for open release of the A1 pulley in the fingers, but in the

thumb a transverse incision is preferred. Percutaneous techniques are being developed for release of trigger digits but

may be less safe in the thumb or index because of the proximity of the digital nerves (123).

Congenital Trigger Digits

Trigger Thumb

Definition

Although a number of diagnoses may be considered when a

child presents with a thumb locked in flexion, including

congenital clasped thumb, arthrogryposis, spasticity, or

absent extensors, the most common cause is congenital trigger thumb. This condition is characterized by a palpable

lump in the region of the A1 pulley; the thumb may be

flexed (the usual posture is interphalangeal joint flexion) or

extended, and rarely is seen to catch or trigger, as opposed

to the adult form of trigger thumb (121,124).

Pathologic Anatomy

The lesion is a nodular thickening in the FPL tendon

referred to as Notta’s node, named after the person who may

have been the first to describe this condition in children

(125). This finding is in distinct contrast to the pathologic

anatomy in the adult. In adults, it is unusual to find a

grossly visible nodule in the tendon, although there may be

some comparative size difference or pseudonodule formation in the tendon proximal to the leading edge of the A1

pulley. An annular indentation of the tendon due to sustained compression of the thickened annular pulley may

result in comparative enlargement of the tendon proximal

to A1.

Treatment

Conservative treatment in the form of splinting, massage,

passive manipulation, and watchful waiting for spontaneous resolution has all been tried with low levels of success.

Surgery in the form of release of the A1 pulley is associated

with a high degree of success (121).

Trigger Fingers

Definition

This condition may be characterized by a history of triggering, decreased active range of motion with a flexion posture

of the PIP joint from 30 to 90 degrees, a palpable nodule

proximal to the A1 pulley, and, in some cases, the finger is

locked in flexion (124,126).

Pathologic Anatomy

Abnormal findings may include a visible nodule in the FDP

tendon, a nodule in the FDS, and bunching up or buckling

of one or both slips of the FDS.

10.1 Palmar Hand 623

FIGURE 10.71. The proximal and distal commissural ligaments

in Dupuytren’s disease. In contrast to the transverse components

of the palmar fascia, the transverse fibers to the thumb web, the

proximal and distal commissural ligaments that are more

obliquely oriented and are subject to tension, may contract and

be responsible for loss of abduction and extension of the thumb.

Treatment

Surgical exposure should be extensile to evaluate the flexor

sheath and tendons from the A1 to A3 pulleys. This permits

release of the A1 pulley, excision of tendon nodules, excision of one or both slips of the FDS, and release of the A3

pulley as required (124). Although Tordai and Engkvist did

not find tendon nodules in their cases, they noted that complete release required more than just release of A1, and

included separation of the slips of insertion of the FDS and

release of the proximal portion of the A2 pulley (126).

Clinical Significance

Trigger fingers in children are much less common than trigger thumbs. In a comparatively large series of trigger digits

in children, 86% were trigger thumbs and 14% trigger fingers (124). In contrast to trigger thumb release in children,

release of the A1 pulley may be inadequate to release triggering, and correction may require excision of tendon nodules, one or both slips of the superficialis tendon, and

release of the A3 pulley. The incision for trigger finger

release should be extensile to allow, as required, thorough

exploration of the flexor tendon sheath and its contents

(124).

Trigger Digits and Hurler’s Syndrome

The anatomic findings in trigger digits due to Hurler’s syndrome is rosary bead–like swelling along the entire tendon

with constrictions at the annular pulleys due to abnormal

deposition of mucopolysaccharide in connective tissues.

Treatment may require more extensive excision of involved

structures (124).

Finger Flexor Pulley Rupture

Incidence

The incidence of this relatively unusual condition appears

to be increasing, perhaps because of the growing popularity

of rock climbing.

Mechanism of Injury

The typical mechanism is a rapidly applied extension force

to an acutely flexed finger (127). This force may be applied

in a variety of conditions, but a typical circumstance has

been identified in rock climbers. Finger holds often are

wide enough to admit only the tips of the fingers, and the

posture required to admit two or more digits to this confined space is with the DIP joints extended and the MCP

and the PIP joints flexed to 90 degrees or more. The

climber’s thumb is flexed over the top. This posture or technique is called crimping and often is used on vertical or

overhanging surfaces (128) (Fig. 10.72).

Biomechanical Factors

The crimping posture puts a large strain on the distal end

of the A2 pulley. Sudden loading of the finger in this posture may exceed the breaking strength of the pulley. Analysis of the forces of a 70-kg man falling and putting his

weight through one finger in the crimping posture produces

a resultant force of 450 N. This force applied at approximately right angles to the long axis of the proximal phalanx

exceeds the mean force of 400 N at which the A2 pulley

failed in a study by Lin et al. (128,129).

Clinical Presentation

In rock climbers with isolated rupture of the A2 pulley,

their main complaint may be a bulge over the proximal

phalanx of the affected finger, and on examination there

may be bowstringing of the flexor tendons across the PIP

joint (128). In other cases there may be a history of something “tearing” in the finger, but with only moderate pain

and no bruising. Later, PIP joint flexion contracture and

bowstringing of the flexor tendons develop (127). Bowers et

al. noted rupture of the A2, A3, and A4 pulleys in seven of

their nine cases, in contrast to the usual isolated rupture of

the A2 pulley noted in rock climbers (127,128). Le Viet et

al. noted rupture of the A2 and A4 pulleys in four of seven

cases, the A2 pulley in two cases, and the A4 pulley alone in

one case (130).

624 Regional Anatomy

FIGURE 10.72. The rock climber’s technique of crimping, which

may be associated with rupture of the second annular pulley.

Diagnosis

In addition to the history and physical examination, the

diagnosis may be confirmed by tomogram, computed

tomography scan, or magnetic resonance imaging, although

the history and physical examination should be adequate to

make the diagnosis (127,130).

Treatment

In acute cases, the pulley rupture may be repaired (131).

Pulley reconstruction may be elected to meet functional

demands. In late cases, PIP joint contracture may require

release (127).

Collateral Ligament Injuries

Thumb Metacarpophalangeal Ligament

Injuries

Ulnar Collateral Ligament Rupture or Avulsion

(Fig. 10.73)

Mechanism of Injury. This injury is due to sudden and

forceful radial deviation (abduction) of the proximal phalanx of the thumb, often secondary to a fall on the outstretched hand with the thumb abducted. It may be associated with activities such as skiing or ball sports (132).

Anatomy of the Ulnar Collateral Ligament Injury. Disruption of the UCL at the distal insertion (with or without

a bone fragment) is five times more common than proximal

tears or disruptions (133). Tears in the substance of the

UCL occur with less frequency. Associated injuries include

tears of the dorsal capsule, partial avulsion of the palmar

plate, or a tear in the adductor aponeurosis. In addition to

providing lateral stability to the MCP joint, the UCL and

RCL play a role in suspending the proximal phalanx. Therefore, disruption of the UCL may result in palmar migration

and rotation (supination) of the proximal and distal phalanx on the intact RCL.

The Stener Lesion. In 1962, Stener described complete rupture of the UCL with interposition of the adductor aponeurosis between the distally avulsed UCL and its site of insertion

(134). This configuration is easy to understand based on the

fact that the UCL is deep to the adductor aponeurosis, and

with avulsion it is carried proximally while the leading edge of

the adductor aponeurosis is carried distally by the deforming

force of injury. When the force abates and the proximal phalanx returns to its normal alignment, the UCL is external

rather than deep to the adductor aponeurosis. Even if this

configuration did not occur, the natural tension in the ligament and subsequent contracture would place it well proximal to its distal attachment and beneath the aponeurosis.

Clinical Significance. Complete disruptions or tears of the

UCL, with or without the Stener lesion, are best treated by

surgical reattachment of the ligament, whereas partial tears

may be treated by closed methods.

Diagnosis and Treatment. The diagnosis is made by noting the mechanism of injury; identifying tenderness,

swelling, or ecchymoses over the ulnar side of the MCP

joint; and noting laxity of the UCL with stress testing.

Local anesthesia may be used to facilitate the stress test. It is

beyond the scope of this text to discuss the methods of

stress testing in detail, except to note that with complete

UCL disruption the MCP joint may be opened with minimal resistance. The basic principle of treatment in complete

ruptures is to reattach the UCL to its anatomic site of insertion.

10.1 Palmar Hand 625

FIGURE 10.73. A: Normal anatomy of the ulnar collateral ligament (UCL) of the metacarpophalangeal (MCP) joint of the

thumb. B: The Stener lesion. Complete rupture of the UCL often

is associated with retraction of the avulsed UCL proximal to the

adductor aponeurosis. This configuration prevents reattachment

of the UCL and results in instability of the MCP joint.

A B

Avulsion Fractures and the Ulnar Collateral Ligament

Injury. Conventional wisdom has indicated that the position of an avulsion fracture as seen with UCL injuries marks

the distal aspect of the disrupted UCL. A widely displaced

fracture fragment would indicate significant displacement

of the UCL and suggest the need for surgical intervention.

A case report that reevaluated this concept revealed (a) a

patient with UCL instability and an undisplaced fracture at

the base of the proximal phalanx with a classic Stener lesion;

and (b) a patient with a minimally displaced fracture at the

ulnar base of the proximal phalanx and a displaced fragment proximal to the adductor aponeurosis. Surgery

revealed the UCL to be attached to the proximal fragment.

The author of this study (quoting reports by Stener in 1963

and 1969) noted that fractures of this type are either avulsion fractures due to UCL disruption or shear fractures at

the base of the proximal phalanx by the palmar portion of

the radial condyle of the metacarpal and with continued

displacement after UCL rupture (135–137).

Clinical Significance. If the fracture seen on radiographs is

a shear fracture, its position is unrelated to the location of

the distal end of the avulsed UCL. A displaced ligament

may occur in the presence of an undisplaced fracture (137).

Treatment Controversies in Acute Ulnar Collateral Ligament Injuries. Cited factors noted to be useful in the

choice of conservative or operative treatment of UCL

injuries are presence or absence of instability as noted by

varying degrees of angulation of the proximal phalanx on

the metacarpal, both clinically and by radiography (stress

testing); presence or absence of a palpable and displaced ligament proximal to the MCP joint; and, if fractures are present, the displacement or nondisplacement of the fragment

and the amount of displacement, the size of the fracture

fragment based on a percentage of the articular surface of

the proximal phalanx, and whether rotation of the fracture

fragment is present. Uncited factors include the personal

bias and favorable or unfavorable experience of the surgeon

with surgical and nonsurgical methods as applied to the

wide range of pathologic anatomy noted in this injury. A

similar controversy applies to stress testing of the UCL

when an undisplaced or minimally displaced fracture is present at the base of the proximal phalanx (138,139). The

most uniformly agreed on indication for surgical intervention is the presence of the Stener lesion, with or without

fracture (139,140).

Author’s Comment. The reader may appreciate the breadth of

this controversy by noting the widely divergent recommendations of Dinowitz et al., who in nine patients with small avulsion fractures associated with UCL injury noted the failure of

prompt and prolonged closed treatment in all instances (141).

All these patients were subsequently operated on with satisfactory outcome (141). These findings are compared with

those of Kuz et al., who in a retrospective questionnaire study

of 30 patients treated by nonsurgical means noted that all

patients were satisfied with their results. Twenty of these

patients were reexamined; three had instability on stress testing, and there was a 25% nonunion rate of the associated fractures of the proximal phalanx (139).

The treatment of this condition may vary based on many

factors, including the patient’s and surgeon’s definition of

success, and the past experience and personal choice of the

surgeon.

The Effect of Repositioning the Origin and Insertion of

the Ulnar Collateral Ligament. The mean anatomic locations of the origin and insertion of the proper UCL were

determined as part of a study to note the effect of moving

the origin or insertion of the UCL on MCP joint range of

motion (142) (see Fig. 10.9).

Proximal Origin (Metacarpal Attachment) Repositioning.

The UCL was detached and repositioned, in sequence, 2

mm palmar and 2 mm proximal from its anatomic origin.

The following effects on radial deviation were noted: Palmar placement of the origin of the UCL increased radial

deviation from a mean of 18 to 27 degrees; proximal placement decreased it from 18 to a mean of 11 degrees. There

was no effect on flexion or extension from displacing the

proximal origins of the UCL.

Distal Insertion (Proximal Phalanx) Repositioning. The

UCL was detached and repositioned in sequence, 2 mm

dorsal, 2 mm distal, and 2 mm palmar. Dorsal displacement

of the UCL insertion (proximal phalanx) increased radial

deviation from 18 to 25 degrees, and distal positioning of

the insertion decreased it from 18 to 10 degrees. Distal

repositioning of the insertion of the UCL decreased MCP

joint flexion from 56 to 47 degrees, and palmar placement

decreased it from 56 to 49 degrees. Dorsal placement of the

insertion had no effect on flexion. Extension and ulnar

deviation were not affected by ligament repositioning.

Nonanatomic reattachment or reconstruction of the

UCL may alter normal MCP joint range of motion. The

origin and insertion landmarks developed by this study

should serve as useful guides in reattachment and reconstruction surgery of the UCL.

Radial Collateral Ligament Disruption

Although injuries to the RCL are less common than UCL

injuries, they also are associated with significant disability.

Mechanism of Injury. The mechanism of injury in disruption of the RCL is forceful adduction or torsion on the

flexed MCP joint (132).

Anatomy of the Radial Collateral Ligament Injury.

Because of the relatively broader abductor aponeurosis

626 Regional Anatomy

compared with the narrower adductor aponeurosis, there is

no potential for soft tissue interposition (the Stener lesion)

with RCL avulsion. In contrast to the UCL, the RCL is

torn with almost equal frequency proximally and distally,

and mid-substance disruption is more common in the RCL

than in the UCL (132,143,144). The abductor aponeurosis

may be disrupted in addition to the RCL (145). Disruption

of the RCL results in palmar migration and pronation of

the proximal phalanx and dorsoradial prominence of the

metacarpal head. In my experience, these findings may not

be as noticeable immediately after the injury, possibly

because of the initial swelling that might mask the deformities, or because these findings occur progressively and

thus may not be prominent in the early phase of this condition.

Diagnosis and Treatment. Diagnosis of the acute injury is

made based on the history of injury, findings of ecchymosis

or tenderness, and a positive instability test. In my experience, RCL injuries tend to be diagnosed late rather than

early compared with UCL injuries. This may be because a

complete disruption of the UCL results in immediate and

significant disability owing to the functional demands

placed on the ulnar side of the thumb, leading to early evaluation. The RCL injury and subsequent dysfunction does

not seem to be as disabling, at least in the beginning, but as

time passes, it becomes increasingly bothersome and is in

fact a significant source of patient complaint and disability.

The basic principle of treatment in complete ruptures is to

reattach the RCL to its anatomic site of insertion. Late diagnosis may require ligament reconstruction by tendon graft.

Dorsoradial Capsule Injury

The following information about this injury is based on a

study of 11 patients by Krause et al. (146).

Mechanism of Injury and Presenting Complaints. The

mechanism of injury includes a direct blow, sports activities, or breaking a fall (146). The primary complaint was

pain over the dorsum of the thumb and limited use.

Physical Findings. All patients in this study demonstrated

tenderness over the dorsoradial aspect of the thumb MCP

joint in the absence of laxity of either the RCL or UCL. In

4 of the 11 patients, there was mild palmar subluxation of

the proximal phalanx, and all 4 of these patients lacked full

active extension of the proximal phalanx.

Treatment and Findings at Surgery. Four patients were

treated successfully by immobilization. Surgery was performed in seven patients because of persistent activity-limiting complaints over the dorsoradial capsule and the findings of palmar subluxation and extensor lag. The

dorsoradial capsule was noted to be redundant or thinned,

or to have an obvious defect. It was repaired by imbrication

or direct closure of the defect, followed by immobilization

for 5 to 9 weeks.

Anatomy of the Dorsoradial Capsule of the Thumb

Metacarpophalangeal Joint. Based on their findings, the

authors proposed two factors that may contribute to this

injury: (a) an anatomic variation in the collateral ligaments

that allows greater MCP flexion, and (b) an area of relative

thinness and weakness in the dorsoradial capsule compared

with the ulnar side of the joint (146). Regarding range of

motion, the authors noted 64 degrees of flexion in the

opposite thumb MCP joint of their patients, compared

with the published normal of 53 degrees (146,147).

Clinical Significance. This diagnosis should be considered in patients with persistent pain at the thumb MCP

joint. Thumbs with greater flexion of the MCP joint are

predisposed to capsular rather than collateral ligament

injuries. Conservative treatment is indicated if no palmar

subluxation or extensor lag exists.

Finger Metacarpophalangeal Ligament

Injuries

Incidence and Etiology

The overall incidence of rupture of the collateral ligaments

of the fingers is much lower than that of ruptures of either

the UCL or RCL. Ruptures most often occur in the small

finger, most likely because of its position as a border digit,

but finger MCP RCL ruptures have been reported in all the

fingers. The usual mechanism of injury is forced ulnar deviation with the fingers flexed (132).

Diagnosis and Treatment

There usually is tenderness along the radial side of the joint

and pain on ulnar stress of the joint. An arthrogram may aid

in diagnosis. Treatment should be based on functional need

and may include primary reattachment, repair, or reconstruction by tendon graft as needed (148).

Complex Dislocations

Three complex dislocations are suitable for discussion in the

context of this text on surgical anatomy: (a) dorsal dislocation of the thumb MCP joint, (b) dorsal dislocation of the

index finger MCP joint, and (c) palmar dislocation of the

finger PIP joint.

Dorsal Dislocation of the Thumb

Metacarpophalangeal Joint

Most dorsal dislocations of the thumb MCP joint are

reducible; irreducible dislocations are due to variety of

interposed structures that either block or trap the proximal

phalanx from returning to its anatomic position.

10.1 Palmar Hand 627

Mechanism of Injury

If the collateral ligaments are visualized as structures that

suspend the proximal phalanx during flexion and extension,

it is easy to speculate that any disruption of the proximal

attachments or restraints to hyperextension may result in

the proximal phalanx going “over the top” with a sufficient

hyperextension force and becoming locked or trapped on

the dorsal surface of the metacarpal. For this to occur, the

palmar plate attachment must be disrupted either at its

proximal aspect or at its insertion into the base of the proximal phalanx. If the palmar plate is disrupted distally, the

accessory collateral ligaments are torn, and this allows the

proximal phalanx and the collateral ligaments to swing dorsally to the top of the metacarpal. If the palmar plate is

detached proximally, it, along with its imbedded sesamoid

bones, is carried dorsally along with the proximal phalanx.

A radiograph that demonstrates sesamoid bones on the dorsal aspect of the metacarpal and adjacent to the base of the

proximal phalanx usually indicates a complex irreducible

dislocation of this joint (Fig. 10.74).

Interposed Soft Tissues

In addition to the palmar plate, other structures that may

be pulled along in this excursion are the adductor pollicis

aponeurosis, including the bony insertion on the ulnar base

of the proximal phalanx; the abductor expansion; and the

two heads of the FPB, which, along with the intact proper

collateral ligaments, may form an entrapment noose around

the neck of the thumb metacarpal and prevent reduction.

The FPL may be entrapped in the joint but usually remains

in the sheath (149).

Treatment

Closed reduction may be attempted, under appropriate

anesthesia, by flexing the wrist and thumb interphalangeal

joint and then pushing the hyperextended proximal phalanx distalward. Longitudinal traction is avoided because it

may “tighten the noose” represented by the various soft tissues around the neck of the metacarpal and prevent reduction. If closed means are not successful, open reduction is

indicated through a dorsal or palmar approach.

Dorsal Dislocation of the Index Finger

Metacarpophalangeal Joint

Dorsal dislocation of the finger MCP joints is unusual. The

most common digit to be involved is the index, followed by

the small finger; dorsal dislocation of the MCP joints of the

central fingers is seen most often with border digit dislocation (132,150).

Mechanism of Injury

The usual mechanism of injury is hyperextension of the finger, often due to a fall on the outstretched hand. The proximal attachment of the palmar plate is torn, and the suspensory effect of the collateral ligaments allows the

628 Regional Anatomy

FIGURE 10.74. Complex dislocation of

the metacarpophalangeal joint of the

thumb. This radiograph reveals sesamoid bones on the dorsal aspect of the

metacarpal, indicating detachment of

the proximal palmar plate with its

imbedded sesamoid bones. These findings usually indicate a complex irreducible dislocation of this joint. In

addition to the palmar plate, other

structures that may be pulled along in

this excursion are the adductor pollicis

aponeurosis, including the bony insertion on the ulnar base of the proximal

phalanx, the abductor expansion, and

the two heads of the flexor pollicis brevis, which, along with the intact proper

collateral ligaments, may form an

entrapment noose around the neck of

the thumb metacarpal and prevent

reduction.

hyperextension force to thrust the proximal phalanx and

palmar plate dorsally to rest on the dorsal aspect of the

metacarpal.

Interposed Tissues

Kaplan identified a four-sided complex of structures that

played a role in trapping the metacarpal head in the palm

(Fig. 10.75). These structures are as follows: radially, the

lumbrical; proximally, the transverse fibers of the palmar

aponeurosis; ulnarly, the flexor tendons; and distally, the

natatory ligaments and the palmar plate.

Diagnosis

It is important to distinguish between complete irreducible

dislocations and reducible subluxations because a subluxation may be converted to a complete and irreducible lesion

by inappropriate reduction maneuvers.

In complete dislocation (the irreducible lesion), the

MCP joint is held in slight to moderate extension; MCP

joint flexion is impossible and the finger is ulnarly deviated.

A prominence may be palpated in the palm that corresponds to the metacarpal head, and the skin may be puckered.

In subluxation (the reducible lesion), the findings are

similar except that the proximal phalanx usually is more

hyperextended, often to 60 to 80 degrees.

Radiographic Findings

In complete dislocations, the radiographic findings may be

minimal in the anteroposterior view; the oblique view usually demonstrates widening of the joint space, and the lateral view may show the complete dislocation. Lateral or

dorsal displacement of the sesamoid in the oblique and lateral views also is an important finding. A tangential Brewerton view of the metacarpal head may aid in detection of

avulsion or other fractures in the region of the metacarpal

head (151).

Treatment

Distinction must be made between subluxation and complete dislocation because the former is reducible by closed

means and the latter is not (132). In subluxation, the prox10.1 Palmar Hand 629

FIGURE 10.75. Complete dorsal dislocation of the index metacarpophalangeal (MCP) joint. A, B:

Note the foreshortened and adducted index finger and the extended proximal phalanx seen in

dorsal dislocation of the index finger MCP joint. C: Note the structures that trap the metacarpal

head.

A

B

C

imal edge of the palmar plate remains palmar to the

metacarpal head. If either hyperextension or traction is used

as part of the reduction technique, the palmar plate may be

drawn dorsally and result in a complete and irreducible dislocation. The proper reduction maneuver is performed by

flexion of the wrist and distal and palmar force on the base

of the proximal phalanx that slides the phalanx over the

metacarpal head (152).

Irreducible dislocations are treated by open reduction.

Kaplan described a palmar approach for this condition

and Becton et al. have described a dorsal approach

(5,153).

630 Regional Anatomy

FIGURE 10.76. Radiographic appearance of dorsal dislocation of the index finger metacarpophalangeal (MCP) joint in the right hand. A: Anteroposterior views of the hand show only minimal

changes in joint space symmetry. B: Oblique views

of the same injury show a widened MCP joint and

extension and adduction of the finger. C: Lateral

view showing a complete dorsal dislocation.

A

B

C

Palmar Subluxation and Dislocation of the

Proximal Interphalangeal Joint

Rotatory Palmar Subluxation

This rare condition represents a longitudinal rent in the

extensor mechanism between the lateral band and the central slip of the extensor tendon that allows the head of the

proximal phalanx to enter the separation and be trapped

(154,155). The displaced lateral band is trapped behind the

palmar aspect of the condyle, resulting in a rotatory deformity of the middle and distal segment of the finger (154)

(Fig. 10.77).

Mechanism of Injury. The mechanism of injury is due to

a combination of forces, including rotation, flexion, and

lateral deviation (154). The PIP joint is most susceptible to

torsional force at 55 degrees of flexion, when the lateral

bands shift palmar to the mid-axis of the proximal phalanx

(156). Thus, the injury probably is sustained with the PIP

joint in moderate flexion. The term subluxation seems

appropriate because the PIP joint is not widely separated.

Diagnosis. The PIP joint is in moderate flexion, the middle and distal phalanges are rotated, and there is swelling

about the PIP joint. A true lateral radiograph of the proximal phalanx demonstrates partial separation of the PIP

joint and obliquity of the middle phalanx due to the rotatory component of this injury (155).

Treatment. Although this condition has been reported to

be irreducible, closed reduction under appropriate anesthesia may be attempted by simultaneous flexion of the MCP

and PIP joints to relax the lateral band, followed by rotation

of the middle phalanx that is opposite to the deformity

accompanied by gradual extension (155,157). If this

maneuver is not successful, open reduction is performed.

Irreducible Rotatory Palmar Dislocation of the

Proximal Interphalangeal Joint

This condition is the more complete or severe form of rotatory palmar subluxation.

The clinical appearance is characterized by almost 90

degrees of flexion at the PIP joint, supination of the distal

aspect of the finger, and inability to reduce the deformity.

Pathologic Anatomy/Mechanism of Injury. Irreducibility

is due to soft tissue interposition of the central slip, which,

along with the ulnar lateral band, is displaced palmar to the

neck of the proximal phalanx (154) (Fig. 10.78). Findings

at surgery reveal the head of the proximal phalanx projecting through an oblique tear in the extensor expansion

between the central slip and the radial lateral band, and the

central slip and ulnar lateral band displaced to lie together

in front of the neck of the proximal phalanx, where they act

as a block to reduction. The UCL is avulsed and the RCL

is intact. As in rotatory palmar subluxation, the mechanism

of injury is a predominantly rotational force. A common

modality of injury is the still-moving and full spin clothes

drier that catches a finger; the finger most often involved is

the index (154).

Treatment of Irreducible Dislocation. The PIP joint is

exposed through a dorsal approach and reduction is

achieved by replacement of the displaced central slip and

lateral band, followed by repair of the rent in the extensor

mechanism.

Reducible Palmar Dislocation of the Proximal

Interphalangeal Joint

Based on clinical studies and cadaver experiments, the

reducible type of palmar dislocation is associated with

10.1 Palmar Hand 631

FIGURE 10.77. Rotatory subluxation

of the proximal interphalangeal joint.

This rare condition represents a longitudinal rent in the extensor mechanism

between the lateral band and the central slip of the extensor tendon that

allows the head of the proximal phalanx to enter the separation and be

trapped and rotated between the displaced lateral band and the central slip.

injury to one collateral ligament, the palmar plate, and

extensor mechanism (usually the central slip insertion of

the extensor tendon) (158,159). Although usually

reducible, it is unstable because of loss of dorsal support

from the central slip and, more important, if not recognized

and treated properly, results in a boutonniere deformity

because of the central slip disruption. Unilateral injury to

the collateral ligament results in rotatory deformity because

of the suspensory effect of the intact collateral ligament.

The mechanism of injury is a varus or valgus stress followed

by a palmar force that dislocates the middle phalanx palmarly. Cadaver experiments that used only an anterior force

without varus or valgus force resulted in avulsion of the

central slip, usually with a fracture fragment and a lesser

incidence of collateral ligament rupture (158).

Clinical Significance

If an anterior dislocation can be reduced, it is important to

know that an injury to the central slip has occurred and

requires appropriate treatment (154,159). Peimer et al.

noted that palmar dislocations of the PIP joint always

injured the extensor mechanism (most often a tear of the

central slip), a collateral ligament, and the palmar plate.

The associated ligament and tendon injury, if not treated,

results in loss of both static and dynamic PIP joint support

manifested by palmar subluxation, malrotation, boutonniere deformity, and fixed flexion contracture (159). Irreducible palmar dislocations usually are not associated with

central slip disruption and may have a more favorable prognosis. Inability to reduce an anterior dislocation is most

likely due to interposition of a part of the extensor mechanism, and can be corrected by surgery. There are two forms

or stages of progression in rotatory injuries: The first or

stage I is a subluxation injury; the second or stage II is an

irreducible dislocation. Based on the experience of both

Eaton and Green and Butler, a closed reduction of stage I

injuries may be attempted in acute cases (155,157). In stage

II or complete dislocations, closed reduction is not advised

(154).

Proximal Interphalangeal Joint

Contracture

Movement in the middle or PIP joint of the fingers may be

the major component in useful finger function (160). Conventional wisdom has taught that the collateral ligament

complex was essential to PIP joint stability and should be

partially removed to avoid PIP joint instability (161). Curtis noted modest permanent improvement in PIP joint

motion after careful excision of a specific segment of the

scarred ligament system (162). Diao and Eaton published

their results with total excision of the PIP joint collateral

ligaments in 1993 (160).

Treatment

Treatment is best performed by the technique of Diao and

Eaton (160) (Fig. 10.79), total collateral ligament excision.

Through 2-cm ulnar and radial mid-axial incisions centered

over the PIP joint, the adjacent lateral bands are mobilized

632 Regional Anatomy

FIGURE 10.78. Irreducible rotatory palmar dislocation of the proximal interphalangeal (PIP) joint. The clinical appearance is characterized by almost 90

degrees of flexion at the PIP joint, supination of the distal aspect of the finger, and

inability to reduce the deformity.

dorsally and the scarred collateral ligaments are excised

from the proximal phalanx origin, the middle phalangeal

insertion, and the palmar plate attachments. Total collateral

ligament excision is supplemented with palmar plate distal

release, extensor tenolysis, and flexor sheath release as

needed.

Results

Diao and Eaton achieved, on average, over twice the preoperative range of motion (38 to 78 degrees) in a series of 16

patients with total collateral ligament excision. No postoperative instability was noted by manual testing and radiographic examination. The authors surmised that the thickening palpable in their postoperative patients lateral to the

condyles was scar that is capable of organizing and remodeling into a new collateral ligament. They also commented

that the fact that thickening could be palpated across the

joint line suggests that there is a postoperative traumatic

fibroblastic proliferation. In two patients not included in

the series who underwent subsequent surgery after initial

collateral ligament resection, the condylar fossa was occupied by obliquely oriented fibrillated structures that

appeared to be very similar to normal collateral ligaments in

architecture, consistency, and function (160).

Compartment Syndrome

A compartment is an anatomic unit that may contain muscle, nerve, or blood vessel with anatomic boundaries formed

by fascia or bone that is capable of sustaining increased

hydrostatic pressure. Compartment syndrome is defined as

a physiologic sequence manifested by increased hydrostatic

pressure that occurs in a closed anatomic compartment and

that compromises tissue viability. The severity of the syndrome is related to the magnitude and duration of the pressure. This abnormal increase in pressure results in ischemia

of both muscle and nerve. Compartments that may be

involved in compartment syndrome in the hand are the

thenar, hypothenar, adductor, lumbrical, central palmar,

and interosseous compartments (Fig. 10.80).

Thenar Compartment

The thenar compartment is covered palmarly by the thenar

fascia, which begins over the palmar surface of the thumb

metacarpal and wraps around the thenar muscles to return

to the deep surface of the thumb metacarpal. The radial

wall of the compartment is formed by the flexor surface of

the thumb metacarpal. The thenar muscles are the APB,

OP, and FPB. Clinical manifestations of thenar compartment syndrome, in addition to the usual findings of

swelling and tenderness, include weakness or limited opposition and flexion of the thumb. The thumb may assume an

exaggerated posture of abduction and extension, and passive motion may cause pain in the thenar eminence.

Hypothenar Compartment

The hypothenar compartment is bound radially by the

ulnar septum of the central palmar compartment, which

blends with the hypothenar fascia (a thinner continuation

of the palmar fascia) and wraps around the hypothenar

muscles to attach to the ulnar and palmar aspect of the

small finger metacarpal. The small finger metacarpal forms

10.1 Palmar Hand 633

FIGURE 10.79. A, B: Total collateral ligament excision for proximal interphalangeal joint contracture.

A

B

the floor of the hypothenar compartment. The hypothenar

muscles are the ADM, FDM, and ODM. Clinical manifestations of hypothenar compartment syndrome, in addition

to the usual findings of swelling and tenderness, include

pain in the region with passive motion of the small finger.

Limited flexion and abduction of the small finger also may

be present.

Adductor Compartment

The adductor compartment contains the adductor pollicis

and is bounded palmarly by the adductor fascia, which

extends radially from the middle finger metacarpal and

inserts on the thumb metacarpal just to the ulnar side of the

FPL tendon. At the distal border, the adductor fascia blends

into the fascia over the first DI muscle. Dorsally, the adductor compartment is covered by the fascia covering the muscles of the first and second interosseous spaces (88).

Clinical manifestations include swelling and tenderness

in the palm distal to the thenar eminence. Because of

swelling or spasm in the adductor, the thumb may rest in

the palm, in contrast to its usual position of moderate

abduction. Stretching the adductor by extension and

abduction of the thumb may produce complaints of pain in

the compartment, and there may be weakness of pinch

because of the adductor’s role in stabilizing the MCP joint

during this activity.

Lumbrical and Central Palmar Compartments

of the Hand

Because of their proximity and shared structural parts, the

lumbrical compartments (canals) are discussed with the

central palmar space of the hand.

The palm contains a triangular (apex proximal), threedimensional configuration of fascia that forms a space in

its proximal aspect and compartments (canals) in its distal

aspect. Radial and ulnar vertical marginal septa from the

palmar aponeurosis separate this central space from the

thenar and hypothenar compartments. The radial marginal septum begins as an extension of the side wall of the

carpal canal and extends distally over the fascia, covering

the adductor pollicis and first DI muscles. It ends at the

proximal phalanx, forming the radial and palmar margins

of the lumbrical compartment (canal) to the index finger.

Proximally, it separates the central palmar space from the

thenar compartment. The ulnar marginal septa begins on

the ulnar side of the carpal canal and is attached to the

shaft of the small finger metacarpal. Proximally, it separates the central palmar space and hypothenar compartment and distally, the flexor sheath. Between these two

marginal septa are seven intermediate septa that, along

with the marginal septa, divide the distal aspect of the

palm into four canals to accommodate the flexor tendons

and four canals to accommodate the lumbricals and neurovascular bundles. The seven intermediate septa are rectangular with a free falciform proximal edge. They are

attached to the underside of the longitudinal and transverse fibers of the palmar fascia and anchored deep in the

hand to the deep transverse metacarpal ligament and

interosseous fascia. Proximally, the intermediate septa

extend into the acute angle between the FDP and the lumbrical and are comparatively short or long to accommodate a distal or proximal origin of the lumbrical. The roof

of the central palmar space of the hand and the lumbrical

compartments is formed by the longitudinal and transverse fibers of the palmar fascia, and the floor by the palmar interosseous fascia and the adductor fascia.

634 Regional Anatomy

FIGURE 10.80. Anatomy of the compartments of the hand. The recognized compartments of

the hand are the thenar, hypothenar, lumbrical, central palmar, adductor, and interosseous.

Clinical Manifestations of Central Compartment

Syndrome

There may be associated swelling and tenderness in the central palm. Increased pressure in the adjacent central space

may cause hypesthesia on the palmar surface of the fingers

because of ischemia in the nerves secondary to increased

pressure. The lumbrical muscles extend the proximal and

distal joints and assist in flexion of the MCP joints. Contraction of the lumbrical pulls the profundus tendon distally, decreases the effectiveness of the profundus, and

allows the lumbrical more easily to extend the PIP and DIP

joints. Compartment syndrome involving the lumbrical

muscles may produce partial reversal of the normal flexion

posture of the finger at the PIP and DIP joints; in more

severe cases, there may be pronounced flexion of the MCP

joint and extension of the PIP and DIP joints (the so-called

lumbrical plus posture). In some cases, the patient may be

unable actively to flex the proximal and distal joints, and

the test for intrinsic contracture may be positive.

Interosseous Compartments

Four interosseous compartments are present in the hand

that contain three palmar interosseous and four DI muscles.

The interosseous muscles are located between the

metacarpal shafts, which form the lateral wall of the compartments, and the floor and roof are formed by the palmar

interosseous and DI fascia, respectively. Clinical manifestations of interosseous muscle compartment syndrome may

be associated with swelling and tenderness on the dorsum

of the hand and may result in an “intrinsic plus hand” manifested by flexion of the MCP joints and extension of the

PIP and DIP joints. Passive extension of the MCP joints

and passive flexion of the interphalangeal joints are limited,

resisted by the patient, and associated with pain.

Treatment of Compartment Syndrome

Suitable incisions and surgical approaches for compartment

releases in the hand are depicted in Figure 10.81. The DI

and palmar interosseous muscles are approached dorsally

through longitudinal incisions. The radial aspect of the

hand is approached through an incision over the index

metacarpal and the ulnar side through an incision over the

ring finger metacarpal. Each space is entered by incision of

the DI fascia; the DI and palmar interossei as well as the

adductor pollicis may be released by this means. The thenar

and hypothenar compartments are approached through

longitudinal incisions over the radial aspect of the thumb

metacarpal and the ulnar aspect of the small finger

metacarpal, respectively. The lumbrical compartments may

be approached through a transverse incision near or in the

10.1 Palmar Hand 635

FIGURE 10.81. Surgical approaches to the hand compartments. A: Approach to the hypothenar

compartment. B: Approach to the lumbrical, central palmar, and adductor compartments.

C: Approach to the thenar compartment. D, E: Approach to the interosseous compartments

surgical anatomy of the liver

surgical anatomy of the breast

surgical anatomy of the lung

surgical anatomy of the kidney

surgical anatomy of the neck

surgical anatomy of the face

surgical anatomy of the nose

surgical anatomy of the heart

surgical anatomy of the head and neck

surgical anatomy of the abdomen

surgical anatomy of the abdomen pdf

surgical anatomy of the abdominal wall

surgical anatomy of the axilla

surgical anatomy of the abdomen lange

surgical anatomy of the anus

surgical anatomy of the aortic arch

surgical anatomy of the head and neck pdf

surgical anatomy of the hand and upper extremity

surgical anatomy of the biliary tract

surgical anatomy of the bronchial tree and pulmonary artery

surgical anatomy of the brachial plexus

surgical anatomy of the body

surgical anatomy of the temporal bone

surgical anatomy of the skull base

surgical anatomy of the temporal bone and ear

surgical anatomy of breast pdf

surgical anatomy of bladder

surgical anatomy of the cervical plexus and its branches

surgical anatomy of the colon

surgical anatomy of the cerebellopontine angle

surgical anatomy of the inguinal canal

immersive surgical anatomy of the craniometric points

surgical anatomy of the nasal cavity and paranasal sinuses

surgical anatomy of the internal carotid artery

relevant surgical anatomy of the chest wall

surgical anatomy of colon ppt

surgical anatomy of cervical lymph nodes

surgical anatomy of the diaphragm

surgical anatomy of duodenum

surgical anatomy of diaphragm ppt

surgical anatomy of diabetic foot

surgical anatomy of neck dissection

surgical anatomy of thoracic duct

surgical anatomy definition

surgical anatomy diploma

surgical anatomy diploma otago

surgical anatomy definition biology

surgical anatomy of the esophagus

surgical anatomy of the eye

surgical anatomy of the eyelids

surgical anatomy of the ear

surgical anatomy of the middle ear

surgical anatomy of esophagus ppt

surgical anatomy of ear ppt

surgical anatomy of external carotid artery

surgical anatomy of elbow joint

surgical anatomy of external inguinal ring

surgical anatomy of the female pelvis

surgical anatomy of the facial nerve

surgical anatomy of the foot

surgical anatomy of the femoral artery

surgical anatomy of the infratemporal fossa pdf

surgical anatomy of the upper face and forehead

surgical anatomy of the pancreas for limited resection

surgical anatomy of the lateral femoral cutaneous nerve

surgical anatomy of the nasolabial fold

surgical anatomy of the groin

surgical anatomy of the gastrocnemius recession (strayer procedure)

surgical anatomy of the gallbladder

surgical anatomy of the thyroid gland

surgical anatomy of gallbladder ppt

surgical anatomy of gallbladder and bile duct

surgical anatomy of parotid gland

surgical anatomy of thyroid gland ppt

surgical anatomy of parotid gland ppt

surgical anatomy of submandibular gland

surgical anatomy of the heart pdf

surgical anatomy of the hand pdf

surgical anatomy of the hip

surgical anatomy of the hand

surgical anatomy of the hepatic arteries in 1000 cases

surgical anatomy of the head and neck janfaza pdf

surgical anatomy of the insula

surgical anatomy of inguinal hernia

surgical anatomy of intestine

surgical anatomy of internal iliac artery

surgical anatomy of inguinal canal slideshare

surgical anatomy of inner ear

surgical anatomy of intussusception

surgical anatomy of the hip joint

surgical anatomy of hip joint ppt

surgical anatomy of knee joint

surgical anatomy of shoulder joint

surgical anatomy of temporomandibular joint

surgical anatomy of stifle joint

surgical anatomy journals

surgical anatomy joseph maclise

surgical anatomy of the knee

surgical anatomy of kidney ppt

surgical anatomy of total knee replacement

kaplan's functional and surgical anatomy of the hand

surgical anatomy of microneurosurgical sulcal key points

surgical anatomy of the liver revisited

surgical anatomy of the larynx

surgical anatomy of the liver ppt

surgical anatomy of the lumbar plexus

surgical anatomy of liver pdf

surgical anatomy of larynx ppt

surgical anatomy of the midcheek and malar mounds

surgical anatomy of the mitral valve

surgical anatomy of the maxilla

surgical anatomy of the male pelvis

surgical anatomy of maxillary sinus

surgical anatomy of mandible

surgical anatomy of mediastinum

surgical anatomy of maxilla ppt

surgical anatomy of middle ear ppt

surgical anatomy of the neck ppt

surgical anatomy of the nose pdf

surgical anatomy of the neck pdf

surgical anatomy of nose ppt

surgical anatomy of the orbit

surgical anatomy of orbit ppt

surgical anatomy of oesophagus

surgical anatomy of oral cavity ppt

surgical anatomy of oral cavity

surgical anatomy of obturator nerve

surgical anatomy of optic canal

surgical anatomy around the orbit

surgical anatomy of superior orbital fissure

surgical anatomy otago

surgical anatomy of the pancreas

surgical anatomy of the prostate

surgical anatomy of the pelvis

surgical anatomy of the petrous apex and petroclival region

surgical anatomy of the porta hepatis

surgical anatomy of the parapharyngeal space

surgical anatomy quiz

surgical anatomy questions

medical surgical unit description

surgical rankings

surgical anatomy of the retroperitoneal space

surgical anatomy of recurrent laryngeal nerve

surgical anatomy of retina

surgical anatomy of radial nerve

surgical anatomy of retroperitoneum

surgical anatomy of right lung

surgical anatomy of radial artery

surgical anatomy of anorectal region

surgical anatomy of the stomach

surgical anatomy of the spine

surgical anatomy of the skin

surgical anatomy of the sacral plexus and its branches

surgical anatomy of the scalp

surgical anatomy of the spleen

surgical anatomy of the shoulder

surgical anatomy of the hepatobiliary system

surgical anatomy of the thyroid and parathyroid glands

surgical anatomy of the trachea

surgical anatomy of the thyroid and parathyroid glands ppt

surgical anatomy of thyroid

surgical anatomy of tmj

surgical anatomy of the ureter

surgical anatomy of the uterus

surgical anatomy of urinary bladder

surgical anatomy of urinary bladder ppt

surgical anatomy of upper limb

surgical anatomy of ureter in female

surgical anatomy of urethra

surgical anatomy of ureter ppt

surgical anatomy of varicose veins

surgical anatomy of vocal cords

surgical anatomy of vertebral column

surgical anatomy of ventricular system

surgical anatomy of aortic valve

surgical anatomy of subclavian vein

surgical anatomy of third ventricle

surgical anatomy of portal vein

surgical anatomy of tricuspid valve

surgical anatomy of abdominal wall ppt

surgical anatomy what is it

wilcox's surgical anatomy of the heart

wilcox's surgical anatomy of the heart pdf

surgical structure of wounds

surgical anatomy of anterior abdominal wall ppt

surgical anatomy round window

surgical anatomy of the dural walls of the cavernous sinus

surgical anatomy of the xray

surgical anatomy of the x-ray tube

surgical anatomy of the yangtze river

surgical anatomy of the youtube

surgical anatomy of the year

surgical anatomy of the yang

surgical anatomy of the youtube video

surgical anatomy of the zipper

surgical anatomy of the zygomatic arch

surgical anatomy of the zygomatic process

hand and upper extremity

hand and upper extremity center

hand and upper extremity rehabilitation

hand and upper extremity rehab

hand and upper extremity surgery

hand and upper extremity alpharetta

hand and upper extremity eye and ear institute

hand and upper extremity rehabilitation a practical guide

hand and upper extremity specialists

hand and upper extremity surgery center

hand and upper extremity atlanta

hand and upper extremity atlanta ga

hand and upper extremity appleton

hand and upper extremity appleton wi

hand and upper extremity splinting principles and methods

miki & alfonso hand and upper extremity center

hand and upper extremity surgeon salary

hand and upper limb broadmeadow

hand and upper limb birmingham children's hospital

hand and upper limb bunbury

hand and upper limb baldivis

hand and upper limb busselton

hand and upper extremity rehabilitation book

hand and upper extremity rehab book

hand and upper limb centre bunbury

hand and upper limb surgeon brisbane

hand and upper limb centre bethesda

hand and upper extremity center of georgia

hand and upper extremity courses

hand and upper extremity center atlanta

hand and upper extremity center of dallas

hand and upper extremity center ga

hand and upper extremity center wexford pa

hand and upper extremity center alpharetta

hand and upper extremity center aliquippa pa

hand and upper extremity doctors

hand and upper extremity surgery of daytona beach

hand and upper limb clinic doctors

dc hand and upper extremity

hand and upper limb clinic london doctors

hand and upper limb rehab sue doman

dr. ratner hand and upper extremity

washington dc hand and upper extremity ambulatory surgery center

dean clinic hand and upper extremity

hand and upper extremity rehabilitation 4th edition pdf

hand and upper extremity rehabilitation 4th edition

hand and upper extremity rehabilitation 3rd edition

elite hand and upper extremity therapy

hand care the upper extremity expert

evidence based hand and upper extremity protocols

evidence based hand and upper extremity protocols pdf

ohio state hand and upper extremity eye and ear institute

rehabilitation of the hand and upper extremity 7th edition pdf

hand and upper extremity fellowship

hand and upper limb function

hand and upper extremity rehab fairfax va

harvard hand and upper extremity fellowship

hand and upper extremity johnson ferry

best hand and upper extremity fellowships

hand and upper extremity rehab fairfax

brisbane hand and upper limb fellowship

rehabilitation of the hand and upper extremity free download

allegheny general hospital hand and upper extremity fellowship

hand and upper extremity georgia

hand and upper extremity rehab gainesville va

hand and upper extremity center of georgia atlanta

cq hand and upper limb gladstone

georgia hand and upper extremity special interest group

hand and upper extremity rehabilitation a practical guide pdf

georgia hand and upper extremity conference 2021

pediatric hand and upper extremity center of georgia

hand and upper extremity hss

texas health hand and upper extremity specialists

hand over hand instruction

hand injury top of hand

techniques in hand and upper extremity surgery

hand-over-hand technique

miami hand and upper extremity institute

idaho hand and upper extremity

institute for hand and upper extremity rehab

what is hand and upper extremity

orthotic intervention for the hand and upper extremity

orthotic intervention for the hand and upper extremity pdf

hand and upper limb joondalup

hand and upper limb centre joondalup

jackson hand and upper extremity center

hand and upper limb clinic st joseph's london

techniques in hand and upper extremity surgery journal

hand swollen on top of hand

dr. king wong hand and upper extremity surgeon

hand and upper limb london

hand and upper extremity rehab llc

hand and upper limb clinic london wait time

hand and upper limb surgery lahore

hand and upper limb clinic london referral form

hand and upper limb clinic london referral

hand and upper limb clinic london fax

lubbock hand and upper extremity therapy

hand and upper limb therapy pte ltd

hand and upper extremity splinting principles & methods

hand and upper limb centre murdoch

hand and upper limb centre midland

hand and upper extremity splinting principles and methods pdf

mgh hand and upper extremity service

advanced hand and upper extremity center maple grove mn

miami hand and upper extremity

hand-upper-extremity-and-microvascular-surgery

ot miri hand and upper extremity

hand and upper extremity center of northeast wisconsin

nbcot hand and upper extremity

north idaho hand and upper extremity

hand and hands difference

hand pain top of hand

hand and upper extremity of georgia

hand and upper extremity osu

hand and upper limb occupational therapy

uw health hand and upper extremity orthopedic clinic

hand and upper limb london ontario

the hand and upper extremity institute of south texas

hand and upper extremity pittsburgh

hand and upper extremity physical therapy

hand and upper limb physiotherapy

hand and upper arm pain

hand and upper extremity rehabilitation pdf

hand and upper extremity center pocatello id

hand and upper extremity rehabilitation a quick reference guide

institute for hand and upper extremity rehab quakertown pa

when your hand is in my hand quotes

hand veins quotes

hand and upper extremity rehabilitation 4th ed book

hand and upper extremity surgeons

hand and upper extremity surgery center atlanta ga

hand and upper extremity therapy center

hand and upper extremity therapy

hand and upper limb therapy

hand and upper limb therapy castle hill

idaho hand and upper extremity therapy

cape cod hand and upper extremity therapy

hand and upper limb clinic thunder bay

urmc hand and upper extremity rehabilitation

uvm hand and upper extremity

uw hand and upper extremity clinic

umass hand and upper extremity

columbia university hand and upper extremity surgery fellowship

ohio state university hand and upper extremity fellowship

vanderbilt hand and upper extremity center

rehabilitation of the hand and upper extremity 2-volume set 7th edition

rehabilitation of the hand and upper extremity 2-volume set

plastic surgery volume 6 hand and upper extremity

hand and upper extremity wexford pa

hand and upper extremity rehabilitation weiss

hand and upper extremity center appleton wi

hand and upper extremity clinic appleton wi

hand and upper limb clinic wa

hand and upper extremity xray

hand and upper extremity youtube

hand and upper extremity yuba city

hand and upper extremity youngsville la

hand and upper extremity zanesville ohio

hand and upper extremity zanesville

hand and upper extremity zone

hand and upper extremity zionsville