PHYSIOLOGY - ear Flashcards
normal hearing range
0-20 dB HL
purpose of ossicles
amplifies sound
profound hearing loss range
> 90 dB HL
where in the cochlea is low sound frequency picked up
what length are the cilia
apex
short cilia
where in the cochlea is high sound frequency picked up
what length are the cilia
opening
long cilia
where are the hair cells (cilia) in respect to the basilar membrane
on top of the basilar membrane, in the organ of corti
which part of the ear is responsible for balance
5 end organs
otolith organs - utricle, saccule
semicircular canals - posterior, lateral, anterior (superior)
which plane does the utricle work in
horizontal
which plane does the sacclue work in
vertical
what are the otolith organs covered in
what are the otolith organs surrounded by
stereocilia
a ‘jelly’ with chalky calcium carbonate crystals in it (otoconia)
what is the significance of cilia and chalky calcium carbonate crystals when the head is moving
the stereocilia start firing APs to the brain when they feel the crystals moving
in the semicircular canals fluid enters when there is movement of the head
what is the fluid
where does the fluid enter
perilymph
ampulla (opening) of semicircular canals
what is the thing that the perilymph fluid moves in the ampulla of the semicircular canals when the head moves
what does this result in
cupula
stereocilia movement = AP generation
when you move your head to the left, which direction does the perilymph move the cupula
what reflex is this called
to the right
vestibulo-ocular reflex (VOR)
what happens to the vestibule-ocular reflex (VOR) in R vestibular neuritis
decreased firing in R ear from neuritis = left is more powerful = brain thinks youre always looking left (bc its the excited side)
how do you test for vestibule-ocular reflex (VOR)
look for nystagmus when patient asked to look straight ahead
which tuning fork do you use to test hearing with rinnes and webers tests
512Hz tuning fork (smallest one)
bc people tend to loose their high pitched hearing
what is rinnes test (describe it)
put tuning fork in front and behind ear and ask which is louder
in rinnes test, what is a normal finding
louder in front of ear than behind ear
air conduction is louder than bone conduction
in rinnes test, what would you find in conductive hearing loss
louder behind ear (on mastoid process) than in front of ear
bone conduction is louder than air conduction (bc there is an obstruction stopping the air getting into the inner ear, but vibrations via the bones can still get into the inner ear)
in rinnes test, what would you find in sensorineural hearing loss
louder in front of ear than behind
air conduction is louder than bone conduction
OR nothing (cant hear either) if severe sensorineural hearing loss
describe webers test
place tuning fork in middle of forehead and ask which side it is louder in
in webers test what is a normal finding
equal sound in both ears
in webers test what is the finding of a conductive hearing loss
louder in the ear with pathology
