Medical Terminology ch. 17

accommodation:

normal adjustment of the eye to focus on objects from far to near. The ciliary body adjusts the lens and the pupil constricts. When the eye focuses from near to far, the ciliary body flattens the lens and the pupil dilates.

aqueous humor:

fluid produced by the ciliary body and found in the anterior chamber. A humor is any body fluid, including blood and lymph

cone:

photoreceptor cell in the retina that transforms light energy into a nerve impulse. Cones are responsible for color and central vision

cornea:

fibrous transparent layer of clear tissue that extends over the anterior portion of the eyeball.

iris:

pigmented layer that opens and closes to allow more or less light into the eye. The central opening of the iris is the pupil

lens:

transparent, biconvex body behind the pupil of the eye. It bends light rays to bring them into focus on the retina

optic nerve:

cranial nerve carrying impulses from the retina to the brain

pupil:

central opening of the eye, surrounded by the iris, through which light rays pass. It appears dark.

refraction:

bending of light rays by the cornea, lens, and fluids of the eye to bring the rays into focus on the retina.

retina:

light-sensitive nerve cell layer of the eye containing photoreceptor cells (rods and cones)

rod:

photoreceptor cell of the retina essential for vision in dim light and for peripheral vision

sclera:

tough, white outer coat of the eyeball

thalamus:

relay center of the brain. optic nerve fibers pass through the thalamus on their way to the cerebral cortex

vitreous humor:

soft, jelly-like material behind the lens in the vitreous chamber; helps maintain the shape of the eyeball

aque:

water

blephar:

eyelid

cor:

pupil

dacry:

tears

kerat:

cornea

lacrim:

tears

ocul:

eye

opthalm:

eye

scler:

sclera (white of the eye)

dipl:

double

mi:

smaller, less

mydr:

widen, enlarge

phot:

light

opia:

vision

hyperopia:

farsightedness

myopia:

nearsightedness

presbyopia:

impairment of vision as a result of old age

cataract:

clouding of the lens, causing decreased vision

glaucoma:

increased intraocular pressure results in damage to the retina and optic nerve with loss of vision

ptosis:

drooping of upper lid margin as a result of neuromuscular problems or trauma

strabismus:

abnormal deviation of the eye

OD:

right eye

OS:

left eye

OU:

both eyes

PERRLA:

pupils equal, round, reactive to light and accommodation

auricle:

flap of ear, the protruding part of the external ear or pinna

cerumen:

waxy substance secreted by the external ear, also called earwax

cochlea:

snail-shaped, spirally wound tube in the inner ear, contains hearing-sensitive receptor cells

eustachian tube:

auditory tube

incus:

second ossicle of the middle ear

labyrinth:

maze-like series of canals of the inner ear. this includes the cochlea, vestibule, and semicircular canals

ossicle:

small bone of the ear, includes the malleus, incus, and stapes

semicircular canals:

passages in the inner ear associated with maintaining equilibrium

stapes:

third ossicle of the middle ear, also called stirrup

tympanic membrane:

membrane between the outer and the middle ear; also called eardrum

acous:

hearing

audi:

hearing

myring:

eardrum

ot:

ear

salping:

eustachian tube

acusis:

hearing

otitis media:

inflammation of the middle ear

tinnitus:

sensation of nosies in the ears

vertigo:

sensation of irregular or whirling motion either or oneself or of external objects

AD:

right ear

AS:

left ear