Hearing & Balance - B Davis Flashcards
where are the cochlea and vestibular apparatus
in the membranous labyrinth
what is the cochlear duct bound by
thick basilar membrane
where is the organ of Corti
cochlear duct
how many rows of inner hair cells does the organ of corti have
1 neatly arranged single row
how many rows of outer hair cells does the organ of corti have
3-4 rows positioned on the basilar membrane
what are the inner and outer hair cells covered by
gelatinous tectorial membrane
what innervated the inner and outer hair cells
the cochlear nerve
the basilar membrane is anchored to the the internal modulus by the
spiral lamina
what neuron bodies of the cochlear nerve fibers are in the spiral ganglia
1st order sensory neuron bodies
the oval window is much smaller than the tympanic membrane, so it does what to compensate for loss between air and liquid
further amplifies energy
pressure waves send vibrations up the _________, around the ______, and back down the _______ where energy is dissipated at the ___________
scala vestibuli
helicotrema
scala tympani
round window
what is tonotopy
mechanical tuning of basilar membrane
what is tonotopic organization
the basilar membrane varies in stiffness and dimensions along its length, causing it to
vibrate at specific points in response to specific frequencies
the basilar membrane is most rigid ________ and responds to _____ frequencies
proximally ; high
the basilar membrane is most pliable ________ and responds to _____ frequencies
distal ; low
inner hair cells are
primary receptors
outer hair cells help with
amplification
1st order sensory neurons innervate
hair cells
1st order sensory neurons have cell bodies housed in
spiral ganglia
central processes synapse at _______________ in _________
ipsilateral cochlear nucleus
pons
2nd order neurons from cochlear nucleus project mostly _____________ to ___________ in ________
contralaterally
superior olivary nucleus
pons
neurons in superior olivary nucleus project rostrally to _________ then __________ in midbrain
lateral lemniscus
inferior colliculus
from the inferior colliculus, auditory neurons project to _______ of the ________
medial geniculate nucleus (MGN)
thalamus
3rd order neurons from MGN project via internal capsule to _________ in __________ of _________
primary auditory cortex
superior temporal lobe
cerebrum
lesions - damage to cochlear nerve or cochlear nucleus in brainstem will result in
ipsilateral deafness
due to presence of some bilateral projections, higher-level lesions along the auditory pathway will not result in __________ , but can affect _________________ and _____________
complete deafness
higher-level auditory processing (speech recognition)
sound localization
conductive hearing loss is
mechanical
conductive hearing loss is a problem with transmitting mechanical vibrations from
air to inner ear
how does conductive hearing loss typically present
loss of acuity (can’t hear faint sounds)
sensorineural hearing loss has to do with damage to
receptors or nerves (hair cells or cochlear nerve fibers)
inner hair cells do ___ regenerate so frequency loss is often ______-
not
permanent
outer hair cells _____ regenerate, they control __________
may
volume threshold
sensorineural hearing loss can present as ______ or ___________
loss of acuity or loss of sensitivity to certain frequencies
loss of acuity is damage to which hair cells
outer hair cells
loss of sensitivity to certain frequencies is damage to _____ or _______
inner hair cells or cochlear nerves
tinnitus is usually due to damage to _________ because nerves are constantly firing at that _______
hair cells
frequency
a cochlear implant is treatment for what kind of hearing loss
sensorineural
external receiver transmits auditory signals to an electrode coil implanted where
in the cochlea
in a cochlear implant, electrodes fire to simulate action of _____ and send signals along _______
hair cells
cochlear nerve
utricle and saccule have receptor organs called
maculae
patch of dense crystals
otoliths
gravitational pull on otoliths when head tilts causes deflection of ________ , which triggers action potential along fibers of ________-
hair cell stereocilia
vestibular nerve
acceleration in horizontal or vertical plane causes ________ of otoliths which triggers _____
intertial lag
hair cells
utricle macula is more sensitive to _____ acceleration
horizontal
saccule macula is more sensitive to _____ acceleration
vertical
semicircular canals have receptors housed in swollen ampullae on each canal called the
ampullary crest
regarding kinetic balance, as the head turns, an inertial lag of endolymph deflects crest and stereocilia of hair cells which triggers an _________ along ____________-
action potential
vestibular nerve fibers
hair cells in maculae/ampullary crests are innervated by
vestibular nerve fibers
1st order sensory neuron cell bodies housed in ____________ , within the internal acoustic meatus
vestibular ganglia
1st order sensory neuron cell bodies in vestibular ganglia synapse at _______ in ______-
ipsilateral vestibular nucleus
pons
2nd order neurons project ______ to form ____ tracts
inferiorly
two
what are the 2 vestibulospinal tracts forms by 2nd order neurons
medial and lateral
medial vestibulospinal tracts descends to ________ levels
cervical spinal cord
lateral vestibulospinal tracts descends to ________ and ________ levels
lumbar and sacral spinal cord
medial vestibulospinal tract stimulates neck muscles to maintain
position of head
lateral vestibulospinal tract stimulates mainly lower limb muscles to maintain
body posture
2nd order neurons also project to what other 3 places
cerebellum
extraocular motor nuclei
ventral posterior inferior nucleus of thalamus
2nd order neurons project to the cerebellum which makes small tweaks to
motor control (posture , head position)
2nd order neurons project to the extraocular motor nuclei which forms what reflex
vestibulo-ocular reflex
what is the vestibulo-ocular reflex
adjustments to eyes to maintain gaze while head moves
3rd order neurons in VPI of thalamus project to the ______ region of ______
posterior
insula
vertigo is often caused from dislodged otoliths drifting through ___________ which interfere with __________ which causes abnormal ________
semicircular canals
ampullary crests
firing
nystagmus is rhythmic eye movements in response to
abnormal vestibular input
normal vestibulo-ocular reflex causes eyes to move to maintain ________ as head ______
fixed gaze
rotates
abnormal vestibulo-ocular reflex can trigger a motor response in the absence of _______ so the eyes do what
this motor response
tick back and forth
what is Meniere’s disease
complex inner ear disease
Ménière’s disease is usually due to an increase in __________ pressure which interferes with normal function of receptors in _____ and _______
endolymphatic
cochlea and vestibule
