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aqueous humor

liquid that flows through the anterior and posterior eye chambers in the space between the cornea and the lens


condition in which the eye cannot bring horizontal and vertical lines into focus at the same time, causing blurry vision, as a result of irregularities in the curvature of the cornea and lens


flap of cartilage and skin that comprises the outer ear; external ear, pinna


snail-shaped organ of the inner ear; the essential organ of hearing


specialized neurons concentrated in the retina's center that receive color, add visual acuity, and require a significant amount of light to function


transparent mucous membrane covering the anterior eye


the transparent front covering of the eye, easily scratched

eustachian tube

the passage from the throat to the middle ear


sense of taste


condition in which light rays focus behind the retina; farsightedness


the "anvil," one of three tiny bones within the middle ear which are set in motion by sound waves


pigmented section over the front of the eyeball that gives the eye its color


the inner ear, including the vestibule, cochlea, and semicircular canals

lacrimal glands

tear ducts


a transparent, crystalline eye structure that converges or scatters light rays before they focus as images on the retina


the "hammer," one of three tiny bones within the middle ear which are set in motion by sound waves

membranes labyrinth

set of tunnels and chambers in the inner ear


nearsightedness; light rays focus in front of the retina


sense of smell

optic disk

eye region that is not light sensitive

organ of corti

small but intricate organ in the inner ear where the transmission of nerve stimuli begins


collectively, the three tiny bones in the middle ear (the malleus, incus, and the stapes) which are set in motion by sound waves


external ear; auricle


hearing loss that occurs with aging


farsightedness that occurs with aging


the sensation of body position in space


drooping or sagging of eyelid


black center of the eye that regulates the amount of light that enters it


the innermost tunic of the eyeball that contains rods and cones and is the origin of the optic nerve. Light rays focus at the retina in normal vision


specialized neurons dispersed throughout the retina, suited to dim light and especially useful in night vision


outer coating of the eyeball, white of the eye

semicircular canal

section of the inner ear that contains hairlike nerve endings that respond to movement and control the sense of balance


the "stirrup," one of three tiny bones within the middle ear which are set in motion by sound waves

tympanic membrane

eardrum, vibrates as sound waves hit it; transmits the vibrations to the ossicles


sensation of rotation or movement of self or surroundings

vitreous humor

a transparent, gelatin-like material that fills the space behind the lens of the eye

optic disk

area of the retina that lacks photoreceptors


heavily pigmented layer that prevents light scattering within the eye

ciliary body

contains muscle that controls the shape of the lens

pinna, external acoustic meatus, tympanic membrane

structures composing the outer ear

cochlea, semicircular canals, vestibule

structures composing the bony or osseous labyrinth

pharyngotympanic tube

allows pressure in the middle ear to be equalized with the atmospheric pressure

semicircular canals, vestibule

contain receptors for the sense of equilibrium

oval window

transmits the vibrations from the stirrup to the fluid in the inner ear

ciliary muscle

structure that alters the shape of the lens for accomodation

fovea centralis

depressed are in the retina that is the point of clearest vision


fluid contained within the membranous labyrinth of the inner ear


fluid in the inner ear contained within the bony labyrinth surrounding the membranous labyrinth

static equilibrium

sense of knowing the position of the head in relation to gravity

cochlear nerve

branch of the vestibulocochlear nerve that carries hearing impulses

optic nerve

nerve that carries visual impulses from the retina to the brain

opthalmic nerve

branch of the fifth cranial nerve that carries impulses of pain, touch, and temperature from the eye to the brain

oculomotor nerve

largest of the three cranial nerves that carry motor fibers to the eyeball muscles


sense of body movement

free nerve ending

receptors that detect changes in temperature

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