auditory system Flashcards
what is the innervation for tensor tympani muscle?
V3
what is the innervation for tensor tympani stapedius muscle?
facial
what is interaural distance?
the difference between the side of the noise and the non noise side.
what are the three chambers of the cochlea?
scala vestibuli
cochlear duct
scala tympani
the scala vestibuli and tympani has type of liquid in it?
perilymph
the cochlear duct has what type of liquid in it?
endolymph
the sensory part of the cochlea is in what tube?
cochlear duct
high frequency sounds activate what part of the cochlea?
the basal end, close to the oval window
low frequency sounds activate what part of the cochlea?
the apical end, far from the oval window
the outer spiral bundles do what?
phase match and interpretation
modulate the signal
what do the inner hair cells do?
transmit the signal
what is the membrane that sits over the hair cells?
tectorial membrane
the auditory nerve will go to what 3 cochlear nuclei?
dorsal
posterovental
anteroventral
from the ventral cochlear nucleus where does the synapse occur?
superior olive
what are the two major divisions of the superior olive of the pons?
medial
lateral
the medial superior olive does what?
location/timing
the lateral superior olive does what?
intensity
from the superior olives where is the next synapse?
inferior colliculus
what three things synapse at the inferior colliculus?
dorsal cochlear nucleus
lateral superior olive
medial superior olive
once you are at the inferior colliculus what is formed?
a full spatial map
integration of sound occurs here
what do the nerves travel in to get to the inferior colliculus?
lateral lemniscus
what are the two aspects to the inferior colliculus?
- central which is tonotopically organized
- shell not tonotopic
what is the medial geniculate?
the nucleus in the thalamus where neurons from the inferior colliculus synapse
what is the brachium of the inferior colliculus?
the tracts that the nerves from the inferior colliculus travel in to get to the medial geniculate in the thalamus
the dorsal nucleus gets to the inferior colliculus faster than the ventral nucleus. This goes to the thalamus and activates other nuclei as well as the amygdala, what does this do?
activates the autonomic pathway to get out of the way
- for the most part not tonotopic
- *remember that you jump first once you hear a loud noise
from the medial geniculate where do the neurons go?
the cortex, on the top portion of the temporal lobe
called primary auditory cortex or Heschls gyrus
is the primary auditory cortex tonotopically organized?
yes
which sound is considered non threatening, how or low frequency?
high frequency
what is the spoken language pathway?
primary auditory cortex->wernicke’s area->broca’s area->motor area
what is the blood supply of wernicke’s area?
MCA(internal carotid) and PCA (vertebral artery)
what is the blood supply of Broca’s area?
MCA only
how is wernicke’s area and broca’s area connected?
arcuate fasciculus which is an associative commissure
descending pathways
from the cortex to the shell of the inferior colliculus which inhibits all the autonomic pathways
-ex. you don’t jump the second time a loud sound is made
what are 3 functions of the descending/feedback pathways?
startle control
sound dampening
sound focusing
peripheral auditory signs and symptoms
hearing loss
tinnitus: perception of noise in the absence of external sound
hyperacusis: low tolerance to sound
Central auditory signs and symtoms
aphasia: language disorders due to brain damage, not motor
hyperacusis, what is it and what causes it?
- low tolerance to sound
- damage to superior olive cochlear efferent or to cranial nerve V or VII
what is aphasias?
language disorder due to brain damage
- comprehension/production of spoken/written vocabulary/grammar
- dominant hemisphere (left)
- Not a disorder of producing speech
most common aphasias
affecting spoken language
major aphasias
broca’s
understands speech
speech: nonfluent, hesitant, impaired naming, broken speech
major aphasias
wernicke’s
impaired speech comprehension
speech is fluent but jargon and often meaningless
-anosognosia: lack of awareness of communication problem
major aphasias
global (wernicke and broca)
impaired speech comprehension
speech: nonfluent: impaired (also impaired writing)
major aphasias
conduction
understands speech
speech: fluent with paraphasias (wrong words)
impaired repetition
