Aud. & Hearing Impairment Flashcards
Anatomy of the auditory system includes what structures?
Structures of the outer ear, middle ear and inner ear (p. 410)
Cartilage framed appendage covered w/ skin that appears around the 6th weak of gestation from 1st and 2nd branchial arches.
The Pinna (Auricle) (p. 410)
What are the 6 major structures of the pinna?
- Helix
- Antihelix
- Concha
- Tragus
- Antitragus
- Lobe ( p. 410)
(look at picture :)
Which nerve innervates the pinna?
trigeminal nerve (CN V)
sensory innervation
(p. 410)
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 EAM is innervated by which CNs?
CNs trigeminal (V), facial (VII), vagus (X). (p. 410)
The tympanic membrane does what?
It transduces sound (p. 410)
What is the function of the outer ear?
It serves an auditory function in which the OE collects sounds and channels it to the middle ear. (p.410)
The OE serves as a natural filter and enhances or boosts higher frequency sounds by how many dB?
10 to 12 dB (p.411)
What is the natural resonance of the concha?
5000 Hz (p. 411)
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)
A six walled air filled cavity within the petrous portion of the temporal bone.
the middle ear (p.411)
The middle ear houses what?
3 ossicles (bones) 5 ligaments 2 muscles (tendons) (p.411)
What does the ossicular chain consist of & 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 5 ligaments that suspend the ossicular chain in the ME?
- superior malleolar
- lateral malleolar
- anterior malleolar
- posterior includal
- annular ligament
(p. 411)
What function do the 2 muscles in the ME serve?
Hold ossicular chain in place and reduce intensity reaching IE by pulling against each other to stiffen system and reducing efficiency of ME. (p. 411)
What are the 2 muscles in the ME?
The tensor tympani and the stapedius muscle (p. 411)
Tensor tympani pulls malleus ______.
medially (p. 411)
Stapedius muscle (smallest muscle in body) pulls stapes _____ and tilts what?
Pulls stapes posteriorly and tilts footplate in oval window (p. 411)
_________= mucosal lined pathway that ventilates the ME through the connection to the nasopharynx.
Eustachian tube (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 & ME muscles increase sensitivity
25 to 27 dB of estimated 30dB is compensated
(p. 411)
Complex structure residing within the petrous portion of the temporal bone
Inner ear (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)
semicircular canals: ________ movement :: utricle/saccule : _________ movement
angular
linear
(p. 412)
a bony canal that surrounds a membranous tube, about 35 mm in length & coils around central core approx 2 3/4 turns.
cochlea (p. 412)
base of cochlea : ____ :: vestibule: ______
largest turn
smallest turn
(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 & 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)
