132 Visual Apparatus and Orbit

1 Frontal bone

2 Nasal bone

3 Lacrimal bone

4 Maxilla (frontal process)

5 Ethmoidal foramina

6 Lesser wing of sphenoid bone

and optic canal

7 Superior orbital fissure

8 Greater wing of sphenoid bone

9 Orbital process of palatine bone

10 Orbital plate of ethmoid bone

11 Inferior orbital fissure

12 Infra-orbital sulcus

13 Nasolacrimal canal

14 Zygomatic bone

15 Frontal sinus

16 Superior rectus muscle

17 Orbital fatty tissue

18 Optic nerve

19 Sclera

20 Inferior rectus muscle

21 Periorbita and maxilla

22 Maxillary sinus

23 Levator palpebrae superioris

muscle

24 Superior conjunctival fornix

25 Superior tarsal plate

26 Inferior tarsal plate

27 Inferior conjunctival fornix

28 Inferior oblique muscle

29 Lateral rectus muscle

30 Medial rectus muscle

31 Superior oblique muscle

32 Nasal septum

33 Middle nasal concha

34 Inferior nasal concha

35 Tenon’s space

36 Ophthalmic artery

37 Cornea

38 Lens

Bones of the left orbit (indicated by different colors).

Frontal section through the posterior part of the orbit.

Sagittal section through orbit and eyeball. (Right: MRI scan.)

Visual Apparatus and Orbit: Eyeball 133

Horizontal section through the human eye (2).

Lens (equatorial aspect),

anterior pole to the right.

Lens (frontal aspect). Note the

magnification effect.

1 Cornea and anterior chamber

2 Iris and lens

3 Transitional zone between corneal

and conjunctival epithelium

4 Conjunctiva of the eyeball

5 Ciliary body

a Ciliary processes (pars plicata)

b Ciliary ring (pars plana)

6 Zonular fibers

7 Ora serrata

8 Vitreous body

9 Retina

10 Choroid

11 Sclera

12 Optic disc

13 Dura mater and subarachnoid space

14 Optic nerve (n. II)

15 Lens (posterior pole)

16 Equator of lens

17 Lens (anterior pole)

18 Canal of Schlemm

19 Ciliary muscle

20 Vena vorticosa

21 Long posterior ciliary artery

22 Retinal pigmented epithelium

23 Central retinal artery and vein

24 Short posterior ciliary arteries

25 External ocular muscle

26 Anterior ciliary artery

27 Iris

Organization of the eyeball.

Demonstration of vascular tunic of bulb

(schematic drawing).

Anterior segment of the eyeball (posterior aspect).

The opacity of the lens is an artifact.

1

134 Visual Apparatus and Orbit: Vessels of the Eye

Fundus of a normal right eye (courtesy of Prof. Okamura, Univ. Eye

Dept., Kumamoto, Japan). Notice, the arteries are smaller and lighter

than the veins.

Fluorescent angiography of the right eye; retinal vessels.

The same eye as above (courtesy of Prof. Okamura, Univ. Eye Dept.,

Kumamoto, Japan).

Diagram of the ophthalmic artery and its branches.

Anterior segment of the human eye (courtesy of Prof. Naumann,

Eye Dept., University of Erlangen, Germany). Note the colored iris

(16) and the location of the lens behind the iris (14).

1 Posterior and anterior ethmoidal arteries

2 Long and short posterior ciliary arteries

3 Optic nerve and ophthalmic artery

4 Central retinal artery

5 Retinal arteries

6 Supratrochlear artery

7 Supra-orbital artery

8 Dorsal nasal artery

9 Anterior ciliary artery

10 Iridial arteries

11 Lens

12 Iridial fold

13 Pupillary margin of iris

14 Anterior pole of lens

15 Lesser circle of iris

16 Greater circle of iris

17 Margin of cornea or limbus

18 Sclera

19 Superior temporal artery and vein of retina

20 Superior nasal artery and vein of retina

21 Superior macular artery

22 Optic disc

23 Inferior macular artery

24 Inferior temporal artery and vein

25 Fovea centralis and macula lutea

26 Superior temporal artery

27 Superior nasal artery of retina 28 Inferior nasal artery

29 Inferior temporal artery

12

13

14

15

16

17

18

6

7

9

8

10

11

9

1

2

3

4

25

5

1

135

3

Visual Apparatus and Orbit: Extra-ocular Muscles

Schematic diagram of the extra-ocular muscles.

Right orbit (from above). Levator palpebrae superioris

muscle has been severed.

Right orbit with eyeball and extra-ocular

muscles (from above). The roof of the orbit has been

removed, the superior rectus muscle and the levator

palpebrae superioris muscle have been severed.

The action of the extra-ocular muscles. Left orbit (anterior aspect).

Left orbit with eyeball and extra-ocular muscles

(anterior aspect). Lids, conjunctiva, and lacrimal apparatus have been removed.

1 Superior oblique muscle

and ethmoid air cells

2 Medial rectus muscle

3 Trochlea

4 Tendon of superior oblique muscle

5 Superior rectus muscle

6 Cornea

7 Eyeball

8 Optic chiasma

9 Optic nerve (intracranial part)

10 Internal carotid artery

11 Common annular tendon

12 Levator palpebrae superioris

muscle

13 Superior rectus muscle

14 Optic nerve (extracranial part)

15 Lateral rectus muscle

16 Nasolacrimal duct

17 Inferior oblique muscle

18 Nasal bone

19 Maxilla

20 Infra-orbital foramen and nerves

21 Zygomatic bone

22 Inferior rectus muscle

A = Superior rectus muscle

B = Inferior oblique muscle

C = Medial rectus muscle

D = Lateral rectus muscle

E = Inferior rectus muscle

F = Superior oblique muscle

136 Visual Apparatus and Orbit: Extra-ocular Muscles

Extra-ocular muscles and their nerves (lateral aspect of left eye). Lateral rectus divided and reflected.

Left orbit with extra-ocular muscles (anterior aspect).

Eyeball removed.

Extra-ocular eye muscles (antero-lateral aspect).

1 Supra-orbital nerve

2 Cornea

3 Insertion of lateral rectus muscle

4 Eyeball (sclera)

5 Inferior oblique muscle

6 Inferior rectus muscle and inferior branch of oculomotor

nerve

7 Infra-orbital nerve

8 Superior rectus muscle and lacrimal nerve

9 Optic nerve

10 Lateral rectus muscle

11 Ciliary ganglion and abducens nerve (n. VI)

12 Oculomotor nerve (n. III)

13 Trochlear nerve (n. IV)

14 Ophthalmic nerve (n. V1) and maxillary nerve (n. V2)

15 Trochlea and tendon of superior oblique muscle

16 Superior oblique muscle

17 Medial rectus muscle

18 Levator palpebrae superioris muscle

19 Superior rectus muscle

20 Inferior rectus muscle

21 Greater alar cartilage

22 Supra-orbital nerve and levator palpebrae superioris muscle

23 Levator labii superioris muscle

Visual Apparatus and Orbit: Visual Pathway and Areas 137

1 Medial olfactory stria

2 Olfactory trigone

3 Lateral olfactory stria

4 Anterior perforated substance

5 Oculomotor nerve (n. III)

6 Mamillary body

7 Cerebral peduncle

8 Lateral geniculate body

9 Medial geniculate body

10 Pulvinar of thalamus

11 Optic radiation

12 Splenium of the corpus

callosum (commissural fibers)

13 Cuneus

14 Olfactory bulb

15 Olfactory tract

16 Optic nerve (n. II)

17 Infundibulum

18 Anterior commissure

19 Genu of optic radiation

20 Optic tract

21 Interpeduncular fossa and

posterior perforated substance

22 Trochlear nerve (n. IV)

23 Substantia nigra

24 Cerebral aqueduct

25 Visual cortex

26 Line of Gennari

27 Gyrus of striate cortex

28 Calcarine sulcus

Frontal section of the striate cortex at the level

of the striate area in the occipital lobe.

Dissection of the visual pathway (inferior aspect). Frontal pole at top, midbrain divided.

138

A

C

B

C

D

Visual Apparatus and Orbit: Visual Pathway and Areas

1 Upper lid

2 Cornea

3 Eyeball (sclera, retina)

4 Head of optic nerve

5 Optic nerve

6 Optic chiasma

7 Infundibular recess of hypothalamus

8 Amygdaloid body

9 Substantia nigra and crus cerebri

10 Cerebral aqueduct

11 Vermis of cerebellum

12 Falx cerebri

13 Lateral rectus muscle

14 Optic canal

15 Internal carotid artery

16 Optic tract

17 Hippocampus

18 Inferior horn of lateral ventricle

19 Tentorium cerebelli

20 Optic radiation of Gratiolet

21 Visual cortex (area calcarina,

striate cortex)

22 Lens

23 Eyeball

24 Ethmoidal cells

25 Optic nerve with dura sheath

26 Cerebral peduncle

27 Aqueduct of mesencephalon

28 Vermis of cerebellum

Horizontal section through the human head

(MRI scan, courtesy of Prof. W. J. Huk, Erlangen, Germany).

Arrows = branches of arterial circle of Willis.

Diagram of the visual pathway and path of the light

reflex.

Horizontal section through the head at the level of optic chiasma and striate

cortex (superior aspect). Note the relationship of hypothalamic infundibulum to optic

chiasma.

139

47

12

51

52

53

53

43

57

56

19

55

54

39

49

48

3-D reconstruction of the human visual system (MRI scan flash 40°, courtesy of Prof. Huk,

University of Erlangen, Germany).

Dissection of brain stem in situ. Left hemisphere has been partly removed (compare with

MRI scan above).

29 Lateral rectus muscle

30 Medial rectus muscle

31 Temporalis muscle

32 Hypophysis (pituitary gland)

33 Midbrain

34 Ciliary nerves (long and

short)

35 Ciliary ganglion

36 Oculomotor nerve

37 Accessory oculomotor

nucleus

38 Colliculi of midbrain

39 Corpus callosum

40 Visual field

41 Retina

42 Lateral geniculate body

43 Frontal lobe

44 Caudate nucleus

45 Medial rectus muscle

46 Lateral rectus muscle

47 Skin

48 Diploe (skull)

49 Dura mater

50 Thalamus

51 Anterior cerebral artery

52 Caudate nucleus

53 Frontal sinus

54 Internal capsule

55 Lentiform nucleus (putamen)

56 Hippocampus

57 Temporal lobe of left

hemisphere

In binocular vision the visual field (40) is projected upon

portions of both retinae (blue and red in the drawing). In

the chiasma the fibers from the two retinal portions are

combined to form the left optic tract. The fibers of the two

eyes remain separated from each other throughout the entire visual pathway up to their final termination in the calcarine cortex (21). Injuries on the optic pathway produce

visual defects whose nature depends on the location of

the injury. Destruction of one optic nerve (A) produces

blindness in the corresponding eye with loss of pupillary

light reflex. If lesions of the chiasma destroy the crossing

fibers of the nasal portions of the retina (B), both temporal

fields of vision are lost (bitemporal hemianopsia). If

both lateral angles of the chiasma are compressed (C), the

nondecussating fibers from the temporal retinae are

affected, resulting in loss of nasal visual fields (binasal

hemianopsia). Lesions posterior to the chiasma (D) (i.e.,

optic tract, lateral geniculate body, optic radiation, or

visual cortex) result in a loss of the entire opposite field of

vision (homonymous hemianopsia).

Visual Apparatus and Orbit: Visual Pathway and Areas

140 Visual Apparatus and Orbit: Layers of the Orbit

Superficial layer of the left orbit (superior aspect). The roof of

the orbit and a portion of the left tentorium have been removed.

Middle layer of the left orbit (superior aspect). The roof

of the orbit has been removed and the superior extra-ocular

muscles have been divided and reflected.

1 Lateral branch of frontal nerve

2 Lacrimal gland

3 Lacrimal vein

4 Lacrimal nerve

5 Frontal nerve

6 Superior rectus

7 Middle cranial fossa

8 Abducent nerve (n. VI)

9 Trigeminal nerve (n. V)

10 Trochlear nerve (intracranial part) (n. IV)

11 Frontal sinus

12 Levator palpebrae superioris muscle

13 Branches of supratrochlear nerve

14 Olfactory bulb

15 Superior oblique muscle

16 Trochlear nerve (intra-orbital part) (n. IV)

17 Optic nerve (intracranial part)

18 Pituitary gland and infundibulum

19 Dorsum sellae

20 Oculomotor nerve (n. III)

21 Midbrain

22 Tendon of superior oblique muscle

23 Eyeball

24 Vena vorticosa

25 Short ciliary nerves

26 Optic nerve (extracranial part)

27 Trigeminal ganglion