1. Figure 23.1 External anatomy of the eye and accessory structures.
Levator palpebrae
superioris muscle
Lacrimal sac
Medial commissure
Orbicularis
oculi muscle
Lacrimal caruncle
Eyebrow
Upper eyelid
Tarsal plate
Lacrimal gland
Palpebral
conjunctiva
Excretory ducts
of lacrimal glands
Lateral commissure
Tarsal glands
Cornea
Lower eyelid
Lacrimal punctum
Palpebral
fissure
Lacrimal canaliculus
Nasolacrimal duct
Inferior meatus
of nasal cavity
Eyelashes
Bulbar
conjunctiva
Nostril
Conjunctival
sac
Orbicularis
oculi muscle

2. Figure 23.2 Extrinsic muscles of the eye.
Axis at
center
of eye
Trochlea
Superior oblique muscle
Superior oblique tendon
Superior rectus muscle
Inferior
rectus
muscle
Lateral rectus muscle
Medial
rectus
muscle
Lateral
rectus
muscle
Inferior
rectus
muscle
Inferior
oblique
muscle
Common
tendinous
ring
Muscle
Action
Controlling cranial nerve
Lateral rectus
Moves eye laterally
VI (abducens)
Medial rectus
Moves eye medially
III (oculomotor)
Superior rectus
Elevates eye and turns it medially
III (oculomotor)
Inferior rectus
Depresses eye and turns it medially
III (oculomotor)
Inferior oblique
Elevates eye and turns it laterally
III (oculomotor)
Superior oblique
Depresses eye and turns it laterally
IV (trochlear) 2

3. Figure 23.3 Internal anatomy of the eye.
Ciliary body
Sclera
Ciliary zonule
(suspensory
ligament)
Choroid
Retina
Macula lutea
Cornea
Iris
Fovea centralis
Pupil
Posterior pole
Optic nerve
Anterior
pole
Anterior
segment
(contains
aqueous humor)
Lens
Central artery
and vein of
the retina
Scleral venous sinus
Posterior segment
(contains vitreous humor)
Optic disc
(blind spot)
Ora serrata
Ciliary body
Ciliary processes
Vitreous humor
in posterior
segment
view
Ciliary
processes
Ciliary muscle
Iris
Retina
Retina
Choroid
Margin
of pupil
Choroid
Sclera
Sclera
Anterior
segment
Fovea centralis
Lens
Lens
(posterior
aspect)
Optic nerve
Cornea
Optic disc
Ciliary zonule
(suspensory
ligament)
Ciliary zonule
(suspensory
ligament) 3

4. Figure 23.4 Microscopic anatomy of the retina.
Pathway of light
Axons of
ganglion
cells
Bipolar
cells
Photoreceptors
Outer segments
of rods and cones
Choroid
Rod
Cone
Nuclei of
ganglion
cells
Ganglion
cells
Amacrine cell
Horizontal cell
Pathway of signal output
Pigmented
layer of retina
Axons of
ganglion cells
Nuclei
of bipolar
cells
Nuclei of
rods and
cones
Pigmented
layer of
retina
Pathway of light 4

5. Figure 23.5 Anatomy of the cow eye.
Adipose (fatty)
cushion
Cornea
Sclera
Optic nerve
Extrinsic muscle
attachments
Ciliary body
Optic disc
Sclera
Lens
Retina (delicate white
membrane overlying
the darkly pigmented
choroid coat, which
contains the tapetum
lucidum)
Anterior portion
Posterior portion
(concavity filled with
vitreous humor) 5