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SPECIAL SENSES. THE EYE. EXTERNAL EYE STRUCTURES. EYELIDS – contain skeletal muscle to open and close eyes. Lined with a thin membrane called the conjunctiva EYELASHES – keep dust out. TEARS. Produced by the lacrimal gland. They are made of water and an
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SPECIAL SENSES THE EYE
EXTERNAL EYE STRUCTURES • EYELIDS – contain skeletal muscle to open and close eyes. Lined with a thin membrane called the conjunctiva • EYELASHES – keep dust out
TEARS • Produced by the lacrimal gland. They are made of water and an enzyme lysozyme.
EYEBALL • Protected in an orbit that is formed by 5 bones
EYEBALL • THERE ARE 6 EYE MUSCLES THAT AID IN EYE MOVEMENT
EYEBALL MOVEMENT CRANIAL NERVES FOR EYE MOVEMENT ARE CN III – OCULOMOTOR NERVE CN IV – TROCHLEAR NERVE CN VI – ABDUCENS NERVE
LAYERS OF THE EYEBALL SCLERA – OUTER LAYER CHOROID – MIDDLE LAYER RETINA – INNER LAYER
SCLERA • THICKEST LAYER • ANTERIOR PORTION IS THE CORNEA • THE CORNEA IS THE 1ST PART OF THE EYE THAT REFRACTS LIGHT RAYS
CHOROID • LENS – FOCUSES LIGHT • IRIS – COLORED PART OF EYE • PUPIL – CENTRAL OPENING • DARK BLUE PIGMENT – PREVENTS GLARE • MUSCLES TO DILATE AND CONSTRICT PUPIL
RETINA • LINES POSTERIOR 2/3 OF EYEBALL • CONTAINS RODS (DETECTS PRESENCE OF LIGHT) • CONTAINS CONES (DETECTS COLOR) • OPTIC DISC
VISION • IMPULSES CONVERGE AT THE OPTIC DISC AND THROUGH THE OPTIC NERVE OF EACH EYE WHERE THEY CONVERGE AT THE OPTIC CHIASMA.
VISION • FROM THE OPTIC CHIASMA, IMPULSES TRAVEL TO THE VISION CENTER OF THE BRAIN – THE OCCIPUT
VISION THE CRANIAL NERVE FOR VISION IS CRANIAL NERVE II – THE OPTIC NERVE
CAVITIES OF THE EYEBALL • POSTERIOR CAVITY • ANTERIOR CAVITY
ANTERIOR CAVITY • BETWEEN THE FRONT OF THE LENS AND THE CORNEA • IT CONTAINS THE AQUEOUS HUMOR THAT PROVIDES NOURISHMENT TO THE EYE
POSTERIOR CAVITY • BETWEEN THE LENS AND RETINA • LARGER OF THE TWO CAVITIES • CONTAINS THE VITREOUS HUMOR, A SEMISOLID SUBSTANCE THAT KEEPS THE RETINA IN PLACE
ERRORS OF REFRACTION A. NORMAL VISION B. FARSIGHTED C. NEARSIGHTED