BIO_2113__Lab_7_notes_Eye_and_Ear

BIO_2113__Lab_7_notes_Eye_and_Ear - BIO 2113 Anatomy and...

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BIO 2113 Anatomy and Physiology Spring Quarter 2010 Lab 7 Eye and Ear Hugh D. Dookwah DVM, PhD Eye and Associated Structures 70% of all sensory receptors are in the eye Most of the eye is protected by a cushion of fat and the bony orbit Accessory structures include eyebrows, eyelids, conjunctiva, lacrimal apparatus, and extrinsic eye muscles Eyebrows Coarse hairs that overlie the supraorbital margins Functions include: Shading the eye Preventing perspiration from reaching the eye Orbicularis muscle – depresses the eyebrows Corrugator muscles – move the eyebrows medially Palpebrae (Eyelids) Protect the eye anteriorly Palpebral fissure – separates eyelids Canthi – medial and lateral angles (commissures) Lacrimal caruncle – contains glands that secrete a whitish, oily secretion (Sandman’s eye sand) Tarsal plates of connective tissue support the eyelids internally Levator palpebrae superioris – gives the upper eyelid mobility Eyelashes Project from the free margin of each eyelid Initiate reflex blinking Lubricating glands associated with the eyelids Meibomian glands and sebaceous glands Ciliary glands lie between the hair follicles Conjunctiva and Lacrimal Apparatus Conjunctiva is a transparent membrane that: Lines the eyelids as the palpebral conjunctiva Covers the whites of the eyes as the ocular conjunctiva Lubricates and protects the eye Lacrimal Apparatus consists of the lacrimal gland and associated ducts Lacrimal glands secrete tears Tears Contain mucus, antibodies, and lysozyme Enter the eye via superolateral excretory ducts Exit the eye medially via the lacrimal punctum Drain into the nasolacrimal duct 1
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Extrinsic Eye Muscles Six straplike extrinsic eye muscles Enable the eye to follow moving objects Maintain the shape of the eyeball Four rectus muscles originate from the annular ring Two oblique muscles move the eye in the vertical plane Summary of Cranial Nerves and Muscle Actions Names, actions, and cranial nerve innervation of the extrinsic eye muscles Structure of the Eyeball A slightly irregular hollow sphere with anterior and posterior poles The wall is composed of three tunics – fibrous, vascular, and sensory The internal cavity is filled with fluids called humors The lens separates the internal cavity into anterior and posterior segments Fibrous Tunic:- forms the outermost coat of the eye and is composed of: Opaque sclera (posteriorly) Clear cornea (anteriorly) The sclera protects the eye and anchors extrinsic muscles The cornea lets light enter the eye 2
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Vascular Tunic (Uvea): Choroid Region Has three regions: choroid, ciliary body, and iris Choroid region:- A dark brown membrane that forms the posterior portion of the uvea; Supplies blood to all eye tunics Ciliary Body :- A thickened ring of tissue surrounding the lens composed of smooth muscle bundles (ciliary
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BIO_2113__Lab_7_notes_Eye_and_Ear - BIO 2113 Anatomy and...

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