Hearing Flashcards
Keeps nervous system continually informed of head movements and position so we maintain our balance
Equilibrium apparatus
Consists of auricle or pinna
External ear
Rim of helix, fleshy dangling part
Lobule (earlobe)
Function of this is to direct sound waves into external acoustic meatus
Auricle
Short tube that extends from the auricle to the eardrum, it’s lined with skin that’s lined with glands and short hairs
Auditory canal
Gland that secretes ear wax (cerumen) that traps foreign objects and repels insects
(Sebaceous and modified apocrine sweat glands )
Ceruminous glands
Boundary between the outer and middle ears
Sound waves makes this vibrate
Tympanic membrane
Eardrum
Lined with mucous membrane and filled with air
Tympanic cavity
Middle ear
Middle ear bones that receives vibration from the tympanic membrane
Ossicles
Mastoid air cells in temporal bone that communicates with posterior part of tympanic cavity (mid ear)
Tympanic Antrum
This connects the middle ear cavity to the nasopharynx so we can equalize pressure between the middle ear cavity and external air pressure
Pharyngotympanic
Auditory tube
Formerly Eustachian tube
When popping our ears while going up a mountain, why is this done?
Auditory tube opens temporarily so middle ear cavity can equalize pressure with the environment
(Allowing tympanic membrane to vibrate freely)
Auditory tube is also a route for..
Which infections can spread from the throat to ear and even reach the brain
Inflammation of middle ear
Otitis media
Smallest bones in body that are in the inner ear
Name them
Auditory ossicles
Malleus, incus, and stapes
Labyrinth
Lies deep in temporal bone and consists of cochlea, vestibule, and semicircular canals
Inner ear
Location of hearing located here
Cochlea
Sense organs of balance
Semicircular canals
Ossicle that has handle attached to eardrum and base fits in oval window
Malleus
This links the ossicles together into a chain that spans the middle ear cavity
Synovial joints
Function of ossicles
Transmits the vibration of the tympanic membrane to the oval window, which sets the fluid of the cochlea into motion (excited hearing receptors)
Muscle that arises from the wall of the auditory tube and inserts on the malleus
Tensor tympani
Muscle that runs from the posterior of the middle ear cavity to the stapes
Smallest skeletal muscle in body
Stapedius
Tensor tympani does what when there’s loud noise
Tenses the ear drum by pulling it medialis
Stapedius does what when there’s loud noise
Impedes the vibration of the whole ossicle chain and limits movement of the stapes in the oval window
Innervated by cranial nerve N (trigeminal)
Tensor tympani
Innervates by facial nerve
Stapedius
Why do the muscles contract when there’s loud noise?
To prevent damage to heading receptors (1st order neurons)
Condition that results if the stapedius is paralyzed (makes noise feel painful)
Hyperacousia
Series of channels that are bored out of temporal bone, filled with fluid, contain fluid filled tube floating inside
Inner ear
Labyrinth
Bony Labyrinth is filled with
Fluid called perilymph (similar to composition of CSF)
Membranous labyrinth are
Tubes that float inside the bony labyrinth and filled with endolymph (fluid similar to intracellular fluid)
What does Endolymph and perilymph do for hearing?
Conduct sound vibrations and respond to mechanical forces occurring during changes in body position and acceleration
Central egg shaped cavity of bony labyrinth that’s suspended by perilymph and utricle and saccules
Vestibule
Vestibule is united by a small duct are two membranous sacs
Saccules and utricle
Receptors that respond to the pull of gravity and changes in position of head
Located in saccules and utricle
Maculae
These project from vestibule
Semicircular canals
Communicates with the utricle anteriorly
Semicircular duct
Swelling at an end of a semicircular duct and houses an equilibrium receptor called
Ampulla
Croats ampullaris
Equilibrium receptor that responds to angular or rotational movements of head
Crista ampullaris
Extends vestibule and coils around Modiolus
Cochlea
Bony pillar in cochlea
Modiolus
Ends blindly at cochlear apex and runs through center of cochlea
Contains corti
Membranous cochlear duct
Receptor organ for hearing
Corti
Bony cochlea divided into 3 chambers/scalae
Scala vestibuli
Scala tympani
And another
What does scala vestibule and tympani have?
Perilymph
Apex of cochlea that separates two scalae
Helicotrema
Composed of highly vascularized mucous membrane that secretes endolymph into the duct
Stria vascularis
Corti is composed of supporting cells and hearing receptor cells called
Hair cells
Modified microbiology that protrude into K rich endolymph
Long ones project into tectorial membrane
Sterocilia
Waves jiggle this, which sits on the corti
Basilar membrane
Cranial nerve that receives electrical impulse from hair cells that are on the tectorial membrane
Cranial nerve 8
Where on the basilar membrane does high frequency Sounds hit
Near base
Where on the basilar membrane does medium frequency
Near middle of basilar membrane
Where on the basilar membrane does low frequency
Near Apex (end of basilar membrane)
Nerve impulses are sent out of ___ to go to cranial nerve 8
Cochlear Divison
After cranial Nerve 8, where does sound go?
Travels to auditory or cochlear nuclei in the medulla oblongata
After medulla oblongata, it ones to thalamus, then where?
Relayed to auditory area of temporal lobe
Step 1 of hearing
Sounds channeled into external auditory meatus and strikes eardrum making it vibrate
Step 2 of hearing
Eardrum vibrating causes malleus to vibrate and then is passed on to incus and stapes
Step 3 of hearing
Stapes vibrates and moves the membrane of the oval window in and out
Step 4 of hearing
Waves in the perilymph of scala vestibuli displaces the vestibular and basilar membranes
Producing waves in the endolymph in cochlear duct
Step 5 of hearing
Waves then jiggle the basilar membrane upon which the organ of Corti sits
Last step of hearing
Movement bends microvilli of the hair class that are embedded in the tectorial membrane and the hair cells send an electrical impulse back to the brain via cranial nerve VIII
