Final Flashcards
Stapedius Muscle location
- originates bony canal within pyramidal eminence (posterior wall)
- attaches to posterior neck of stapes
- when contracted origination point will stay in place and pull attachment toward it
Tensor Tympani Muscle location
- originates semicanal within anterior wall
- slightly superior to eustachian tube
- attaches superior aspect of manubrium
How are stapedius and tensor tympani muscles activated?
- vocalizations
- chewing
- yawning
- acoustical approximately 70 to 90 dB SL
- air or water stimulation
- tactile and similar stimulation of ears and parts of face
What activates tensor tympani muscles?
- intense acoustic stimulus
- sound that produce startle response
Ipsilateral reflex pathways
- -Cochlea
- Auditory nerve
- ventral cochlear nucleus
- medial nucleus of the facial nerve
- facial nerve
- stapedius nerve
- -Cochlea
- Auditory nerve
- ventral cochlear nucleus
- superior olivary complex
- medial nucleus of the facial nerve
- facial nerve
- stapedius nerve
Contralateral reflex pathways
- -cochlea
- auditory nerve
- ventral cochlear nucleus
- superior olivary complex
- (cross over)
- medial nucleus of the facial nerve
- facial nerve
- stapedius nerve
- -cochlea
- auditory nerve
- ventral cochlear nerve
- (cross over)
- superior olivary complex
- medial nucleus of the facial nerve
- facial nerve
- stapedius nerve
Acoustic Reflex Theories
- protection theory
- perceptual theory
- multifunctional desensitization, interference, injury protection theory
What is the protection theory?
if sounds become too loud the muscles contract to protect the ear from damage
What is perceptual theory?
improves auditory perception- freq. response of conductive mechanism is smoothed, improves attention to acoustic environment, attenuates low freq. internal sounds
What is multifunctional desensitization, interference, injury protection theory?
reduces unimportant sounds to prevent interference during eating, talking, yelling, etc., to hearing acoustic message
Acoustic reflex testing involves:
- use of immittance meter (220/226 Hz probe tone)
- tonal or noise stimuli
- elicitation of stapedial reflex
- admittance change
Benefits of ipsilateral testing?
- sensitive to middle ear pathology
- ears independently evaluated, can measure individual pathways
- effective with young children who are difficult to test
Benefits of contralateral testing?
- sensitive to disorders involving crossed reflex pathways
- less prone to artifact
- greater available normative data
What would cause negative pressure and conductive pathologies?
- absent acoustic reflexes occur most often
- could be elevated acoustic reflexes
Acoustic reflex test responses:
- monophasic
- biphasic at onset
- biphasic at onset and offset
What is monophasic?
a decrease in admittance which results in an increase in impedance
What is biphasic at onset?
brief increase of admittance followed by decrease in admittance
What does biphasic at onset and offset mean?
an abnormal response
What are Artifact Responses?
deflections caused by other activity as opposed to admittance measures
Artifact Responses:
- additive artifact
- subtractive artifact
- additive and subtractive artifacts
What are additive artifacts?
stimulus and probe tones combine to increase level of probe tone and mimics decrease in admittance
What are subtractive artifacts?
stimulus and probe tone combine to decrease level of probe tone and mimics increase in admittance
Drugs that influence reflex results
- barbiturates
- alcohol
- chloropromazine
- curare
What is the accoustic reflex threshold?
lowest level sound that elicits acoustic reflex response
Acoustic reflex threshold norms?
85-110 dB SL (70-90 dB HL)
What kind of acoustic reflex response do conductive disorders cause?
- elevated
- absent
Relationship between acoustic reflex thresholds and hearing thresholds?
- acoustic reflex thresholds constant with hearing thresholds up to about 50 dB HL
- acoustic reflex thresholds increase with hearing thresholds above 50 dB HL
- 70 to 90 dB SL to the pure tone thresholds
What is Acoustic Decay?
reduction in acoustic reflex magnitude during presentation of sustained stimulus
Procedure of acoustic decay testing?
- ipsi and contra stimulation
- record 10 sec response
- 10 dB SL to the acoustic reflex threshold
- test at 500 and 1000 Hz
What is the criteria for positive acoustic decay?
response falls equal to or less than 50% of initial response magnitude during 10 sec stimulus
What are otoacoustic emissions?
noninvasive objective measures of (nonlinear biological mechanism within the cochlea) outer hair cell function
What do OAEs differentiate between?
sensory or neural loss
Problems with OAEs?
Sensitive to agents that influence cochlear function such as noise, ototoxicity, presbycusis
What are the generators of OAEs?
- external canal
- middle ear
- cochlea
- efferent system
Types of OAEs?
- spontaneous
- evoked
- transient evoked
- distortion products
What are spontaneous OAEs?
occur without external acoustic stimulation, no clinical value
What are evoked OAEs?
constant pure tone frequency is introduced at low level, no clinical value
What are transient evoked OAEs?
broad band stimulus produces time locked simultaneous response from basal to apex
What are distortion product OAEs?
present 2 stimuli simultaneously to produce a distortion at a different location in the cochlea, produce distortion frequency at a lower frequency
What kind of audiogram would you expect with a flat tymp?
could see up to a max conductive component of 60 dB HL depends on the amount and consistency of the fluid in the ME
What kind of audiogram would you expect with a negative pressure tymp?
- conductive component at low frequencies
- possibly 250= 20 dB HL, 500= 15 dB HL, 1000= 10 dB HL
What kind of audiogram would you expect with a flat with negative pressure tymp?
conductive component across all frequencies, lows will be worse,20 to 40 dB HL loss
What kind of audiogram would you expect with a negative pressure (-180), eustachian tube dysfunction, tymp?
conductive component at low frequencies
What kind of audiogram would you expect with a flat peak, wide width, tymp?
conductive worse low frequencies than high frequencies
