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Physiology Ch. 12 (The Ear)

Introduction to the Human Body Ch. 12- The Ear
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outer ear
part of ear which collects sound waves and directs them to the external auditory canal and includes the pinna/auricle, external auditory canal, and eardrum/tympanic membrane
auricle
a skin-covered flap of elastic cartilage that plays a small part in collecting sound waves and directing them towards the external auditory canal
external auditory canal
a curved tube in the temporal bone connecting the outer and middle ears
ceruminous glands
modified sweat glands, located in external ear canal, secretes cerumen (earwax)
cerumen
Earwax, substance secreted by the ceruminous glands in the external auditor canal of the external ear
tympanic membrane
(eardrum) A structure that separates the outer ear from the middle ear and vibrates in response to sound waves.
middle ear
the chamber between the eardrum and cochlea containing three tiny bones (hammer [malleus], anvil [incus], and stirrup [stapes]) that concentrate the vibrations of the eardrum on the cochlea's oval window
Eustachian tube
(auditory tube) connects the middle ear with the upper part of the throat.
auditory ossicles
3 smallest bones in the body, Malleus, Incus, Stapes. transmit the sound vibrations from the eardrum to the oval window and the round window which connect to the middle and inner ear
oval window
membrane across the opening between the middle ear and inner ear that conducts vibrations to the cochlea
inner ear
part of the ear that contains the liquid filled cochlea; here sound vibrations are converted into electric impulses that travel through a nerve to the brain. Divided into the (outer) bony labyrinth and (inner) membraneous labyrinth.
bony labyrinth
series of cavities in the temporal bone, (cochlea, vestibule, and semicircular canals) and contains perilymph.
membraneous labyrinth
a series of sacs and tubes with the same general shape as the bony labyrinth. contains endolymph.
vestibule
oval-shaped middle part of the bony labyrinth. The membraneous labyrinth in the vestibule consists of the utricle and saccule.
utricle
larger of two sacs within the membranous labyrinth of the vestibule in the inner ear that contains the receptor organ for static equilibrium
saccule
smaller of two sacs within the membranous labyrinth of the vestibule in the inner ear containing a receptor organ of static equilibrium
semicircular canals
three bony channels (anterior, posterior, lateral), filled w/ perilymph, in which lie in the membraneous semicircular canals filled with endolymph. They contain receptors for equilibrium.
ampulla
the dilated portion of a canal or duct especially of the semicircular canals of the ear
semicircular ducts
the membraneous semicircular canals filled w/ endolymph and floating in the perilymph of the bony semicircular canals; they contain cristae that are concerned with dynamic equilibrium.
cochlea
the sense organ for hearing. A bony spiral canal that is divided into the scala vestibuli (begins at oval window), the scala tympani (ends at round window), and the cochlear duct.
round window
a small opening between the middle and internal ear, directly inferior to the oval window, covered by the secondary tympanic membrane
organ of Corti
(spiral organ), organ of hearing that consists of hair cells and supporting cells that rest on the basilar membrane and extend into the endolymph of the cochlear duct.
equilibrium
a state of balance
static equilibrium
the maintenance of the posture in response to changes in the orientation of the body, mainly the head, relative to the ground, (A form of equilibrium where there are no processes occurring anywhere in the system.)
dynamic equilibrium
the maintenance of body position, mainly the head, in response to sudden movement, such as rotation. (A condition that is stable within certain levels)
vestibular apparatus
collective term for the organs of equilibrium, which includes the saccule, utricle, and semicircular ducts.
maculae
small, thickened regions in the walls of the saccule and the utricle.
hair cells
Sensory receptors found in the inner ear. Cochlear hair cells respond to vibration in the cochlea caused by sound waves and vestibular hair cells respond to changes in position and acceleration (used for balance).
supporting cells
cells that support hair cells
otolithic membrane
thick, gelatinous, glycoprotein layer located directly over hair cells of the macula in the saccule and uricle of the internal ear
otolith
calcium carbonate particles embedded in the otolithic membrane that functions in maintaining static equilibrium
vestibular branch
conducts nerve impulses to the vestibulocochlear branch
crista
a crest or ridged structure. a small elevation inthe ampulla of each semicircular duct that contains receptors for dynamic equilibrium
cupula
a mass of gelatinous material covering the hair cells of a crista; a sensory receptor in the ampulla of a semicircular canal stimulated when the head moves
Deafness
partial or complete loss of hearing. Sensorineural deafness: caused by the impairment if hair cells in the cochlea or damage of the cochlear branch of the vestibulocochlear nerve. Conduction deafness: caused by impairment of the outer and middle ear mechanisms for transmitting sounds to the cochlea.
Meniere's disease
Collection of fluid in the labyrinth of the inner ear and a degeneration of the hair cells in the cochlea and vestibule
Otitis Media
an acute, ear infection caused by bacteria from the throat