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
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
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
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
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