Figure 23 1 External anatomy of the eye

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 Tarsal glands Cornea Lateral commissure Lower eyelid Lacrimal punctum Palpebral fissure Lacrimal canaliculus Nasolacrimal duct Eyelashes Inferior meatus of nasal cavity Bulbar conjunctiva Nostril Conjunctival sac Orbicularis oculi muscle © 2014 Pearson Education, Inc.

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 Common tendinous ring Inferior oblique muscle Muscle © 2014 Pearson Education, Inc. 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)

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 Scleral venous sinus Optic disc (blind spot) Posterior segment (contains vitreous humor) Central artery and vein of the retina Ora serrata Ciliary body Ciliary processes Vitreous humor in posterior segment Iris Retina Margin of pupil Choroid Anterior segment Lens Cornea Ciliary zonule (suspensory ligament) © 2014 Pearson Education, Inc. view Ciliary processes Ciliary muscle Retina Choroid Sclera Fovea centralis Optic nerve Optic disc Lens (posterior aspect) Ciliary zonule (suspensory ligament)

Figure 23. 4 Microscopic anatomy of the retina. Pathway of light Axons of ganglion cells Bipolar cells Ganglion cells Photoreceptors • Rod • Cone Nuclei of ganglion cells Outer segments of rods and cones Choroid Amacrine cell Horizontal cell Pathway of signal output Pathway of light © 2014 Pearson Education, Inc. Pigmented layer of retina Axons of ganglion cells Nuclei of bipolar cells Nuclei of rods and cones Pigmented layer of retina

Figure 23. 5 Anatomy of the cow eye. Adipose (fatty) cushion Cornea Sclera Optic nerve Extrinsic muscle attachments Ciliary body Optic disc Sclera Lens Anterior portion © 2014 Pearson Education, Inc. Posterior portion (concavity filled with vitreous humor) Retina (delicate white membrane overlying the darkly pigmented choroid coat, which contains the tapetum lucidum)