CSD 460: Exam 1 - Middle Ear

what are the bony parts of the middle ear called

ossicles

what are 3 ossicles in the middle ear

malleus, incus, stapes

which is the biggest ossicle

malleus

which is the smallest ossicle

stapes

what is the main function of the middle ear

impedence matching

which ossicle is in contact with the eardrum

malleus

which ossicle is in contact with the oval window of the cochlea

stapes

ossicles are suspended by ___

ligaments

ossicles route sound vibrations striking the eardrum directly to the ___

oval window

what are the 2 middle ear muscles

stapedius muscle and tensor tympani muscle

what is the main function for the middle ear muscles

protect the ear from noise damage

what is the stapedius muscle attached to

stapes

what is the tensor tympani attached to

malleus

what does the stapedius muscle contract to

loud sound

what does the tensor tympani contract to

touch to lateral air and air pressure changes in the EAC

what is the stapedius innervated by

facial nerve (CNVII)

what is the tensor tympani innervated by

trigeminal nerve (CNV)

tensor tympani originates from ___ wall of the cavity

anterior

stapedius originates from ___ wall of the cavity

posterior

what are the purposes of the eustachian tube

equalize air pressure and drain fluids into nasopharynx

eustachian tube connects the ME to the ___

upper part of the throat (nasopharynx)

how much of the eustachian tube is encased in bone

1/3

how much of the eustachian tube is encased in cartilage

2/3

the eustachian tube is normally __

closed

the eustachian tube normally sits at a ___ degree angle for an adult

45

why are children more susceptible to middle ear infections

children’s eustachian tube sits horizontally making it harder for fluids to drain

what imbalances air pressure

colds, allergies, and changes in elevation

what two muscles help open/close the eustachian tube

tensor veli palatini and levator veli palatini 

which eustachian tube muscle allows it to open/close

tensor veli palatini

which eustachian tube muscle allows it to elongate/shorten

levator veli palatini

with a eustachian tube, it allows for ____ to occur

air exchange

An eustachian tube that’s always open is called ___

patulous eustachian tube

what is the the most common disorder of the middle ear, which causes conductive hearing loss and is seen in 70% of children in the USA before they reach age 2

otitis media

If fluid pressure builds in the middle ear, the tympanic membrane faces the threat of perforation. Which procedure is done to avoid this?

insertion of P.E. tubes

if the eustachian tube is swelled shut, in order for air pressure to leave, it goes through _____

pars flaccida of the TM

what 2 mechanisms does sound go through in the ME to compensate for loss of energy

areal ratio and complex lever system

what parts of the ME is the areal ratio applied to

eardum/tympani membrane and footplate of stapes

how much sound is recovered because of areal ratio

25 dB

what ossicles are the complex lever system applied to

malleus and incus (long process)

how much sound is recovered because of the complex lever system

2 dB

because our ears have air-cochlear fluid mismatch, our ears have developed a ____

middle ear (ME) transfer function

the ossicles overcome loss of sound by increasing what

pressure

what is the reflex that allows for the stapedius muscle to contract in both ears even if only one ear was stimulated

consensual reflex

what reflex allows for muscles that are meant to block sound to activate

acoustic reflex

what is 1

malleus

what is 3

incus

what is 6

stapes

what is 8

eustachian tube

what is 5

stapedius muscle

what is 9

tensor tympani musclehw

what is 7

tympanic cavity