Ear Flashcards
2 parts of auditory system
CENTRAL AUDITORY NERVOUS SYSTEM; PERIPHERAL AUDITORY NERVOUS SYSTEM
From Cochlear nucleus to primary auditory cortex
Central ANS
CN VIII
Auditory Nerve
Auditory nerve is a ____ process
neural
auditory nerve function
Transmits auditory and vestibular info from ear to brain
collection of auditory nerve fibers
Spiral ganglion
Peripheral ANS consists of
outer, middle, inner ear
Outer ear is a _____ process
acoustic
pinna function
sound localization
External auditory meatus function
sound amplifier
outer ear terminates at
tympanic membrane
Cerumen function
traps and repels
Outer ear function
resonator and amplifier
Middle ear is a _____ process
mechanical
3 layers of tympanic membrane
epidermal, fibrous, and membranous
ossicular chain
malleus, incus, stapes
2 middle ear muscles
Stapedius (CN VII) Tensor tympani (CN V)
Opens to equalize pressure
Eustachian Tube
Middle ear function
conduction, protection
Inner ear is a ______ process
Hydromechanical, Chemical
2 subdivisions of cochlea
Osseous bony cochlea
Membranous cochlea
Inner ear function
converts mechanical sound waves to electrical activity and neural impulses
testing that measures the range and sensitivity of an individual’s hearing
Audiometry
in air conduction testing, sounds go
through outer and middle ear
presentation of pure tone testing
headphones, external
When air conduction threshold in one ear exceeds bone conduction threshold in contralateral ear by 40dB HL or more
Air conduction masking
sound through bone vibration direct to cochlea/inner ear
bone conduction testing
bone conduction testing presentation
Bone oscillator behind ear instead of headphones
use with Children who can’t complete a normal hearing screening and/or if hearing loss is suspected in the brain/brain pathway
Auditory Brainstem Response (ABR)
Auditory Brainstem Response (ABR) presentation
Electrodes: placed on head, record brain activity in response to sounds
Intensity at which signal is barely detectible 50% of the time
threshold
used to determine hair cell function
Otoacoustic emissions
OAEs presentation
Earphone/probe inserted into ear (that makes sounds); OAEs record the response to that sound by vibration
Dip in audiogram at 2,000 Hz due to stapes fixation
Carhart’s notch
Average of 500, 1000, and 2000 Hz thresholds
Pure tone average
If sharply sloping loss, use ____ (average of 2 best thresholds at 500, 1000, and 2000 Hz)
fletcher average
identifies the site of damage of the auditory system
Type
3 types of HL
conductive, SNL, mixed
outer and middle ear damage makes what loss
conductive
conductive HL if air bone gap greater than
10 dB
conductive HL if bone threshold
WNL
inner ear and/or CN VIII makes what loss
SNL
When Air + bone thresholds are equal, what type
SNL
refers to the severity of the hearing loss
degree of HL
the extent and pattern of loss across frequencies
Configuration
AC thresholds within 20 dB of each other
Flat
AC thresholds for low frequencies at least 20 dB poorer than for high frequencies
Rising
AC thresholds for high frequencies at least 20 dB poorer than for low frequencies
Sloping
HL only found in the low frequencies
Low frequency
HL only found in the high frequencies
High frequency
High frequency thresholds worsen by at least 20 dB per octave
Precipitous
measurement of the eardrum immittance as a function of air pressure in the ear canal
Tympanometry
Tympanometry procedure
A soft rubber tip (probe) is inserted into the ear canal, changing the pressure in the ear canal
The admittance of the middle ear system (mobility); height of peak;
Static admittance
The point at which air pressure is equal on either side of tympanic membrane
Tympanic peak pressure
Describes the steepness and shape of the slope of the tympanogram, near the peak
Tympanic width
Estimates the volume of the air medial to the probe
Canal volume
normal tympanogram
Type A
Shallow compliance tymp
Type As
Type As tymp indicates:
Middle ear fluid, otosclerosis
Deep compliance tymp
Type Ad
Type Ad tymp indicates
Ossicular disarticulation;
TM scaring
Flat tymp
Type B
Type B tymp indicates
Middle ear effusion;
Perforated TM;
Cerumen occlusion
negative pressure tymp
Type C
Type C tymp indicates
Negative pressure TM or middle ear;
Eustachian tube dysfunction
