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Chapter 17: Sense Organs: The Eye and the Ear
Normal adjustment of the eye to focus on objects from far to near.
Area behind the cornea and in front of the lens and iris. It contains aqueous humor.
Fluid produced by the ciliary body and found in the anterior chamber.
Any body fluid, including blood and lymph
Consisting of two surfaces that are rounded, elevated, and curved evenly, like part of a sphere. The lens of the eye is a biconvex body.
Middle, vascular layer of the eye, between the retina and the sclera.
Structure surrounding the lens that connects the choroid and iris. It contains ciliary muscles, which control the shape of the lens, and it secretes aqueous humor.
Photoreceptor cell in the retina that transforms light energy into a nerve impulse. Cones are responsible for color and central vision.
Delicate membrane lining the undersurface of the eyelids and covering the anterior eyeball.
Fibrous transparent layer of clear tissue that extends over the anterior portion of the eyeball.
Tiny pit or depression in the retina that is the region of clearest vision.
fundus of the eye
Posterior, inner part of the eye.
Pigmented layer that opens and closes to allow more or less light into the eye. The central opening of the iris is the pupil.
Transparent, biconvex body behind the pupil of the eye. It bends (refracts) light rays to bring them into focus on the retina.
Yellowish region on the retina lateral to and slightly below the optic disc; contains the fovea centralis, which is the area of clearest vision.
Point at which optic nerve fibers cross in the brain (chiasm means crossing).
Region at the back of the eye where the optic nerve meets the retina. It is the blind spot of the eye because it contains only nerve fibers, no rods or cones, and is thus insensitive to light.
Cranial nerve carrying impulses from the retina to the brain (cerebral cortex).
Central opening of the eye, surrounded by the iris, through which light rays pass. It appears dark.
Bending of light rays by the cornea, lens, and fluids of the eye to bring the rays into focus on the retina.
Light-sensitive nerve cell layer of the eye containing photoreceptor cells (rods and cones).
Photoreceptor cell of the retina essential for vision in dim light and for peripheral vision.
Tough, white outer coat of the eyeball.
Relay center of the brain. Optic nerve fibers pass through the thalamus on their way to the cerebral cortex.
Soft, jelly-like material behind the lens in the vitreous chamber; helps maintain the shape of the eyeball.
ciliary body or muscle of the eye
tears, tear duct
optic disc; nipple-like
lens of the eye
lens of the eye
uvea; vascular layer of the eye
Defective curvature of the cornea or lens of the eye.
Impairment of vision as a result of old age.
Clouding of the lens, causing decreased vision.
Small, hard, cystic mass on the eyelid
Retinal effects of diabetes mellitus include microaneurysms, hemorrhages, dilation of retinal veins, and neovascularization (new blood vessels form in the retina).
Increased intraocular pressure results in damage to the retina and optic nerve with loss of vision.
hordeolum (stye or sty)
Localized, purulent, inflammatory staphylococcal infection of a sebaceous gland in the eyelid.
Progressive damage to the macula of the retina
Repetitive rhythmic movements of one or both eyes.
Inflammation of the eyelid, causing redness, crusting, and swelling along lid margins.
Blockage, inflammation, and infection of a nasolacrimal duct and lacrimal sac, causing redness and swelling in the region between the nose and the lower lid.
Outward sagging and eversion of the eyelid, leading to improper lacrimation and corneal drying and ulceration.
Inversion of the eyelid, causing the lashes to rub against the eye; corneal abrasion may result.
Drooping of upper lid margin as a result of neuromuscular problems or trauma
Raised yellowish plaque on eyelid caused by lipid disorder
Two layers of the retina separate from each other.
Abnormal deviation of the eye
Intravenous injection of fluorescein (a dye) followed by serial photographs of the retina through dilated pupils.
Visual examination of the interior of the eye
slit lamp microscopy
Examination of anterior ocular structures under microscopic magnification
visual acuity test
Clarity of vision is assessed
visual field test
Measurement of the area (peripheral and central) within which objects are seen when the eyes are fixed, looking straight ahead without movement of the head.
Removal of the entire eyeball
Surgical repair of the cornea
Intense, precisely focused light beam (argon laser) creates an inflammatory reaction that seals retinal tears and leaky retinal blood vessels.
Use of an excimer laser to correct errors of refraction (myopia, hyperopia, and astigmatism). LASIK is an acronym for LASer In situ Keratomileusis.
Ultrasonic vibrations break up the lens, which then is aspirated through the ultrasonic probe.
Suture of a silicone band to the sclera over a detached portion of the retina.
Removal of the vitreous humor.
Channel that leads from the pinna to the eardrum.
auditory nerve fibers
Carry impulses from the inner ear to the brain (cerebral cortex). These fibers compose the vestibulocochlear nerve (cranial nerve VIII).
Channel between the middle ear and the nasopharynx; eustachian tube.
Flap of the ear; the protruding part of the external ear, or pinna.
Waxy substance secreted by the external ear; also called earwax.
Snail-shaped, spirally wound tube in the inner ear; contains hearing-sensitive receptor cells.
Fluid within the labyrinth of the inner ear
Second ossicle (bone) of the middle ear; incus means anvil.
Maze-like series of canals of the inner ear. This includes the cochlea, vestibule, and semicircular canals.
First ossicle of the middle ear; malleus means hammer.
organ of Corti
Sensitive auditory receptor area found in the cochlea of the inner ear.
Small bone of the ear; includes the malleus, incus, and stapes.
Membrane between the middle ear and the inner ear
Fluid contained in the labyrinth of the inner ear.
Auricle; flap of the ear
Passages in the inner ear associated with maintaining equilibrium
Third ossicle of the middle ear. Stapes means stirrup.
Membrane between the outer and middle ear; also called the eardrum
Central cavity of the labyrinth, connecting the semicircular canals and the cochlea. The vestibule contains two structures, the saccule and utricle, that help to maintain equilibrium.
hearing; the sense of hearing
eardrum, tympanic membrane
eustachian tube, auditory tube
eardrum, tympanic membrane
instrument to measure
Benign tumor arising from the acoustic vestibulocochlear nerve (eighth cranial nerve) in the brain.
Collection of skin cells and cholesterol in a sac within the middle ear.
Loss of the ability to hear.
Disorder of the labyrinth of the inner ear; elevated endolymph pressure within the cochlea and semicircular canals.
Inflammation of the middle ear.
Hardening of the bony tissue of the middle ear.
Sensation of noises (ringing, buzzing, whistling, booming) in the ears.
Sensation of irregular or whirling motion either of oneself or of external objects.
Testing of the sense of hearing.
cochlear implant procedure
Surgical insertion of a device that allows sensorineural hearing-impaired persons to understand speech
Measurement of the temperature of the tympanic membrane by detection of infrared radiation from the eardrum.
Visual examination of the ear canal with an otoscope.
tuning fork test
Test of ear conduction using a vibration source (tuning fork)