Aud. & Hearing Impairment Flashcards
The external auditory meatus (EAM) is an s-shaped oval canal ___ to ___ mm in length. It opens at the ______ and terminates at the _____________.
25 to 33 mm
pinna
tympanic membrane
(p. 410)
The tympanic membrane does what?
It transduces sound (p. 410)
What is the function of the outer ear?
collects sounds and channels it to the middle ear. (p.410)
Besides auditory function, what other function does the OE serve?
protection
- cerumen ‘noxious’ to introders
- s-shape prevents foreign objects from reaching ME and TM (p. 411)
What does the ossicular chain consist of and what does it do?
3 bones (smallest in human body)
transfers the mechanical vibrations from TM to inner ear
p. 411
______= the most lateral ossicle, consisting of manubrium, head, neck and lateral and anterior processes; attached to the TM and the incus.
Malleus (p. 411)
______ = the middle and largest bone in the ossicular chain consisting of a body and a short, long, and lenticular process.
Incus (p. 411)
______= the most medial third and smallest ossicle consisting of a head, footplate, and 2 crura. The footplate is held in the oval window by annular ligament.
Stapes (p. 411)
What are the 2 muscles in the ME?
The tensor tympani and the stapedius muscle (p. 411)
impedance mismatch = ?
loss of sound energy (p. 411)
How does the ME compensate for impedance mismatch? How much is compensated?
two primary mechanisms –> lever effect and ME muscles increase sensitivity
25 to 27 dB of estimated 30dB is compensated
(p. 411)
What are the 2 functions of the IE?
sense of hearing (cochlea) and sense of balance (semicircular canals and otolithic organs) (p. 411)
a bony canal that surrounds a membranous tube, about 35 mm in length and coils around central core approx 2 3/4 turns.
cochlea (p. 412)
________= upper canal running from oval window to helicotrema; contains perilymph
scala vestibuli (p. 412)
_______= lower canal running from the round window to helicotrema; contains perilymph
scala tympani (p. 412)
______= middle canal divided from scala vestibuli by Reissner’s membrane and from scala tympani by basilar membrane; contains organ of corti and contains endolymph.
scala media (p. 412)
The organ of corti consists of ?
sensory hair cells, support cells and support membranes and ligaments (p. 412)
How many (sensory) Outer Hair Cells (OHC) are there approx?
13,500 per ear; housed in 3 to 4 rows (p. 412)
The OHC serve as?
biologic modifier increasing or decreasing sensitivity to sounds by changing length of hair cells ( p. 412)
How many (sensory) Inner Hair Cells (IHC) are there approx?
3500 per ear housed in 1 row (p. 412)
The IHC serve as?
serve to process frequency, temporal and intensity info to auditory pathway (p. 413)
The basilar membrane yields what?
Tonotopicity in which high frequencies are processed at the base and low frequencies at the apex (p. 413)
What is the tectorial membrane responsible for?
For shearing the stereocilia of the hair cells (p. 413)
What is the main function of the IE?
Changes the mechanical energy into hyrdomechanical energy and then into neural impulses (p. 413)
Middle Ear contains what?
tympanic membrane Malleus Incus-Middle bone Stapes Tensor tympani Stapedius muscle Eustachian tube connects middle ear to nasopharynx
What does Inner Ear house?
Oval window
Labyrinths
Vestibular system
Cochlea
Cochlea
- -inner ear
- -Contains basilar membrane, organ of Corti, cilia
- -Receives wavelike movements that transform them into electrical energy that can stimulate nerve endings and carry sound to the brain
Oval window
- -inner ear
- -Beginning of inner ear
- -Small opening in temporal bone that houses inner ear.
Labyrinths
- -in inner ear
- -Interconnecting tunnels in inner ear that are filled with perilymph
Vestibular system
- -inner ear
- -3 semicircular canals responsible for equilibrium