Approach to Hearing Loss Flashcards
(23 cards)
Where do sound waves enter?
External auditory canal
After entering the external auditory canal the sound wave does what?
Bounces off the tympanic membrane
What does the tympanic membrane move?
Malleus, incus, stapes
What does movement of the stapes footplate cause?
Changes in pressure in the fluid-filled inner ear that triggers a traveling wave in the basilar membrane of the cochlea
How does hearing occur through bone conduction?
Vibration of bones in the skull
How does the traveling wave in the basilar membrane move?
From the base to the apex of the cochlea
Where is the Organ of Corti found? What is found inside?
Inside the cochlea on the basilar membrane
Hair cells with stereocilia
What are the hair cells in contact with?
Tectorial membrane
What deforms the hair cells?
Traveling wave of sound
Where do high frequency tones maximally displace the basilar membrane?
Near the base of the cochlea
As frequency of sound decreases, the point of maximal displacement moves where?
Toward the apex of the cochlea
Distortion of the stereocilia causes?
Depolarization of the cell and results in increased electrical activity along the auditory nerve
Category of hearing loss?
Conductive
Sensorineural hearing loss
Conductive hearing loss?
Transmission of sound through air is blocked
Otosclerosis?
Bony overgrowth of the stapes at its point of attachment to the cochlea that causes the ossicles to stiffen and fail to transmit sound vibrations from the tympanic membrane
Sensorineural hearing loss?
Arises primarily from damage to hair cells in the organ of Corti
Presbyacusis?
Age related hearing loss that is gradually progressive and involves mostly high frequency sounds
What does Meniere’s disease produce?
Vertigo, fluctuating sensorineural hearing loss, and tinnitus
Pathogenesis of Meniere’s disease?
Decreased resorption of endolymphatic fluid causes fluid buildup or hydrops with high pressure, bowing, and subsequent rupture in the membrane separating the endolymph from the perilymph
What happens when the two fluids mix in Meniere’s disease?
Bc they have two different compositions the mixture produces a sudden change in vestibular cochlear pressure and in their electrical firing properties
Most common cause of tympanic membrane perforation?
Infection
In TM perforation what does the degree of hearing loss depend on?
Size of the hole
Otosclerosis Onset? Which ears? FHx?
20-30
Bilateral
Positive
