study guide - 21:22 External accessory structures: Eyelids...

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21:22 External accessory structures: Eyelids (Palpebrae): help with protecting the eye Lateral and Medial corners: angle of the eye Caruncle: a small, red portion of the corner of the eye that contains modified sebaceous and sweat glands. Eyelashes: richly innervated by nerve endings, has reflex blinking Oribicularis oculi: muscle that closes the eye, innervated by CN7 Tarsal plates: give the eyelids their curved shape and serve as attachment sites for the oribularis oculi Levator Palpebrae Superioris: innervated by CN 3, skeletal muscle that voluntarily opens the eye, runs anteriorly form the posterior roof of the orbit, enters the upper eyelid and inserts on the tarsal plate Superior Tarsal Muscle: innervated by CN 3, sympathetic innervation, inferior part of the aponeurosis, smooth muscle Conjuctival Sac: slit like space that forms between the eye surface and the eyelid, where contacts hide Palpebral conjuctiva: transparent mucous membrane that covers the inner surface of the eyelids Bulbar conjuctiva: covers the white of the eye but not the cornea, very thin membrane and blood vessels are clearly visible beneath it Lacrimal apparatus: Lacrimal gland: produces lacrimal fluid (tears), which enters the superior part of the conjunctival sac through several small excretory ducts, goes lateral to medial across the eyes, moisten and protects the eye, drains into the lacrimal apparatus Lacrimal puncta: tiny opening in the medial angle Lacrimal canaliculi: small tubes that the lacrimal punctum empties into Lacrimal sac: where the lacrimal canaliculus empties into which is in the medial orbital wall Nasolacrimal duct: empties the fluid into the nasal cavity at the inferior nasal meatus Production of tears: lacrimal gland lacrimal puncta lacrimal canaliculi lacrimal sac nasolacrimal duct nasal cavity
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Wall of the eyeball: Fibrous layer: o Sclera: white part of the eye o Cornea: transparent, because the collagen fibers line up, lots of nerve endings, bends entering light Vascular layer: o subdivisions choroid: vascular pigmented membrane ciliary body/muscle: lens accommodation iris: colored part of the eye, consists of the dilator and sphincter pupilae, the round central opening is the pupil o components pigment blood vessels smooth muscle o muscles ciliary: sphincter pupillae: constricts, parasympathetic innervation, innervated by CN 3 dilator pupillae: dilates and is sympathetic stimulation Sensory layer (retina): o layers pigmented: absorbs light and prevents scatter
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neural: contains photoreceptor cells and focuses images o photoreceptors rods: we have numerous, sensitive to light, “gray and fuzzy” cones : less numerous, high light level, acute vision, color (red, blue, green) o optic disc (blind spot): can’t focus on image, no receptor cells, where the optic nerve leaves eye and goes to the brain o macula lutea: yellow spot, where the fovea centralis lies o
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This note was uploaded on 04/04/2011 for the course ANATOMY 1 taught by Professor Peburn during the Fall '09 term at Missouri (Mizzou).

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study guide - 21:22 External accessory structures: Eyelids...

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