Anterior view, muscles removed to expose pronator quadratus

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190

There are two

muscle groups

in the posterior

Posterior Antebrachial Muscles

antebrachium — the eight muscles of the lateral group that share a common attachment on or near the

lateral epicondyle of the humerus and the four muscles of the radial group that course along the distal

aspect of the radius to insert on the thumb and fi rst fi nger. Like the triceps of the posterior brachial

compartment, all the muscles of the posterior antebrachium receive innervation via the radial nerve.

With a few exceptions, the muscles are extensors of either the elbow, wrist, or digits.

Posterior Antebrachial Muscles

 1 Brachioradialis

 2 Anconeus

 3 Supinator

 4 Extensor carpi radialis longus

 5 Extensor carpi radialis brevis

 6 Extensor digitorum

 7 Extensor digiti minimi

 8 Extensor carpi ulnaris

 9 Abductor pollicis longus

10 Extensor pollicis longus

 11 Extensor pollicis brevis

12 Extensor indicis

Other Muscles and Structures

13 Biceps brachii

14 Brachialis

15 Triceps brachii

16 Flexor carpi radialis

17 Pronator teres

18 Flexor pollicis longus

19 Abductor digiti minimi

20 Dorsal interossei

Superfi cial muscles of the right antebrachium

Posterior view, hand pronated

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191

Deep muscles of the right antebrachium

Posterior view, lateral group muscles removed and hand pronated

Deep muscles of the right antebrachium

Anterolateral view, lateral group muscles removed and hand pronated

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192

There are three muscle groups in the hand — the muscles of the thenar eminence

at the base of the thumb, the muscles of the hypothenar eminence at the base of

the little fi nger, and the three layers of intermetacarpal muscles that occupy the

Hand Muscles

spaces between the metacarpal bones. All of these muscles arise from the anterior muscles of the embryonic limb bud and

receive anterior division nerve supply from the median and ulnar nerves as they pass from the anterior antebrachium into

the hand. While the median nerve supplies the majority of the muscles of the anterior antebrachium, the ulnar nerve supplies

all but three of the muscles in the hand.

Superfi cial muscles of the right hand

Anterior view

Muscles of the

thenar eminence

Muscles of the

hypothenar eminence 12 13

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193

Intermediate muscles of the right hand

Anterior view

Hand Muscles

 1 Abductor pollicis brevis

 2 Flexor pollicis brevis

 3 Adductor pollicis

 4 Abductor digiti minimi

 5 Flexor digiti minimi brevis

 6 Palmaris brevis

 7 Lumbricals

 8 Palmar interossei

 9 Dorsal interossei

Other Muscles and Structures

10 Flexor digitorum superficialis

 11 Flexor digitorum profundus

12 Palmaris longus

13 Flexor carpi ulnaris

14 Flexor pollucis longus

15 Flexor carpi radialis

16 Palmar aponeurosis

17 Flexor retinaculum

18 Ulna

Muscles of the

thenar eminence

Muscles of the

hypothenar eminence

Intermetacarpal muscles

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194

Hand Muscles

Deep muscles of the right hand

Anterior view

Muscles of the

thenar eminence

Muscles of the

hypothenar eminence

Intermetacarpal muscles

Hand Muscles

 1 Abductor pollicis brevis (cut)

 2 Flexor pollicis brevis (cut)

 3 Opponens pollicis

 4 Adductor pollicis

 5 Abductor digiti minimi

 6 Flexor digiti minimi brevis

 7 Opponens digiti minimi

 8 Palmaris brevis

 9 Lumbricals (cut)

10 Palmar interossei

 11 Dorsal interossei

Other Muscles and Structures

12 Flexor digitorum superficialis

13 Flexor digitorum profundus

14 Carpal tunnel

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Th e design of the inferior limb

musculature is similar to that of the true limb muscles of the superior limb.

Th e major diff erence between the two limbs is that the proximal end of the

lower limb forms a direct skeletal attachment to the vertebral column via the

strong sacro-iliac joint, unlike the unattached scapula of the superior limb.

Because of this diff erence, the inferior limb does not require body wall muscles to support, stabilize, and suspend it from the axial skeleton. Th ere are

two additional features that are important to keep in mind when studying

this powerful locomotor limb. First, during development of the lower limb

the embryonic posterior muscles rotate and reposition themselves to the

anterior aspect of the limb. For this reason the knee and ankle move directly opposite the elbow and wrist. Th e second notable feature is that

there are three muscle compartments in the thigh and leg, as compared

to just two in the brachium and antebrachium. One of the two original

compartments in each lower limb segment (thigh and leg) splits to give

rise to an additional compartment. Th e thigh has an anterior compartment and a posterior compartment, but the posterior compartment is

subdivided into posterior and medial compartments. Th e leg has a large

posterior compartment and a smaller anterior compartment and the

 anterior compartment is subdivided into anterior and lateral compartments. As with the upper limb, we present the muscles of the lower limb

proper in their muscle compartments. Again, this greatly simplifi es the

learning process because most of the muscles in a compartment share similar attachments, perform common actions, and have a common nerve supply.

Unlike the compartmental muscles of the lower limb proper, the proximal

 muscles of the lower limb that surround the hip joint are a more diverse group of

muscles. Some are true limb muscles, while others are annexed muscles from the

trunk wall. We organize these hip muscles into three groups — the deep hip rotator

muscles, the gluteal muscles, and the hip fl exors.

Find more information

about the muscles of the

lower limb in

REAL ANATOMY

195

Lower Limb Muscles

196

the lower limb to the scapular muscles of the upper limb. Like the shoulder muscles, the muscles surrounding the hip joint

are a varied group of muscles, with some annexed from the body wall of the abdominopelvic region. In the limb proper the

muscles develop in muscular compartments as they do in the upper limb; however, the embryonic posterior aspect of the

limb rotates to an anterior position. As a result, the nerves that arise from the posterior divisions of the lumbosacral plexus

innervate the anterior muscle compartments, and the nerves from the anterior divisions of the plexus innervate the posterior

muscle compartments. The developmental groups of muscles and their nerve supply are outlined below.

The muscles of the lower limb share similarities with their

upper limb counterparts, yet have important differences. As

you will notice in the groups below there are no homologues in

Lower Limb Muscles

Hip Muscles

 Gluteal muscles

(Nerve supply - gluteal nerves, superior to maximus and inferior

to the other three; arise from lateral aspect of ilium and are prime

movers and stabilizers of hip joint)

 Gluteus maximus

 Gluteus medius

 Gluteus minimus

 Tensor fasciae latae

 Deep hip rotator muscles

(All are lateral rotators of the hip joint and insert on the medial

aspect of greater trochancter)

 Piriformis

 Obturator internus

 Obturator externus

 Superior gemellus

 Inferior gemellus

 Quadratus femoris

 Hip flexor muscles

 Psoas major

 Iliacus

Anterior Thigh Muscles

(Nerve supply - femoral nerve; major extensor group of the knee)

 Sartorius

 Quadriceps femoris

 Rectus femoris

 Vastus lateralis

 Vastus intermedius

 Vastus medialis

 Articularis genu

Medial Thigh Muscles

(Nerve supply - obturator nerve with exception of pectineus, which is

supplied by femoral nerve and condylar head of adductor magnus,

which is supplied by tibial nerve)

 Pectineus

 Adductor brevis

 Adductor longus

 Adductor magnus

 Adductor minimis

 Gracilis

Posterior Thigh Muscles

(Nerve supply - Tibial nerve with exception of short head of biceps

femoris, which is supplied by common fibular nerve)

 Biceps femoris

 Semitendinosus

 Semimembranosus

Anterior Leg Muscles

(Nerve supply - deep fibular nerve)

 Tibialis anterior

 Extensor digitorum longus

 Extensor hallucis longus

 Peroneus tertius

Lateral Leg Muscles

(Nerve supply - superficial fibular nerve)

 Peroneus longus

 Peroneus brevis

Posterior Leg Muscles

(Nerve supply - tibial nerve)

 Triceps surae

 Gastrocnemius

 Soleus

 Plantaris

 Popliteus

 Tibialis posterior

 Flexor digitorum longus

 Flexor hallucis longus

Dorsal Foot Muscles

(Nerve supply - deep fibular nerve)

 Extensor hallucis brevis

 Extensor digitorum brevis

Plantar Foot Muscles

(Nerve supply - tibial nerve via its terminal branches, medial plantar

nerve supplies first lumbrical, abductor hallucis, flexor hallucis brevis,

and flexor digitorum brevis; lateral plantar nerve supplies all the others)

 First layer

 Abductor hallucis

 Flexor digitorum brevis

 Abductor digiti minimi

 Second layer

 Quadratus plantae

 Lumbricales

 Third layer

 Flexor halluci brevis

 Adductor hallucis

 Flexor digiti minimi brevis

 Fourth layer

 Plantar interossei

 Dorsal interossei

197

Muscles of the lower limb

Anterior view

 1 Tensor fasciae latae

 2 Iliacus

 3 Psoas major

 4 Pectineus

 5 Adductor longus

 6 Gracilis

 7 Sartorius

 8 Rectus femoris

 9 Vastus lateralis

10 Vastus medialis

 11 Gluteus maximus

12 Adductor magnus

13 Biceps femoris

14 Semitendinosus

15 Semimembranosus

16 Gastrocnemius

17 Soleus

18 Tibialis anterior

19 Fibularis longus

20 Fibularis brevis

21 Iliotibial tract

22 Calcaneal tendon

23 Quadriceps tendon

24 Flexor digitorum longus

Muscles of the lower limb

Posterior view

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