Neuro (03.30) Auditory and Vestibular System Flashcards
what is similar between hearing and balance?
periperal sensing
two divisions of CN VIII
- cochlear
- vestibular
division of CN VIII dealing with sound
cochlear
division of CN VIII dealing with head position and movement
vestibular
both divisions of CN VIII innervate highly specialized organs w _____ called ____ ____ that sense different mechanical stimuli
- mechanoreceptors
- hair cells
auditory and vestibular receptors are located in walls of membranous ____ ___ structure. they are embedded in the ____ bone and suspended in the ___ ___
- inner ear
- temporal
- bony tube (bony labyrinth)
the cochlea is ___ and extends to an enlargement, _____
- coiled
- vestibule
the three semicircular canals are attached at the ____
vestibule
cochlear duct is in the ___
cochlea
semicircular duct is found in each ___ ___
semicircular canal
what are the two enlargements of the membranous labyrinth
- utricle (semicircular ducts attached)
- saccule (connected to cochlear duct and utricle)
the perilymph fills the ___ ____ and is similar to ____
- bony labyrinth
- CSF
the endolymph fills the ____ ____ and is similar to ___ ____
- membranous labyrinth
- intracelluar fluid
___ ____ in hair cells (and other cells) keep perilymph and endolymph separate establishes voltage and concentration gradients needed for transduction
tight juncitons
produced continuously by specialized cells in cochlea and circulates
endopymph
endolymph is resorbed in the ____ ____
endolymphatic sac
obstruction of flow out endolymph results in swelling of ____ ____
membranous labyrinth
transient attacks of vertigo, nausea, hearing loss, tinnitus (ear ringing)
meniere’s disease
*cause is unknown and likely multiple
hair cells have specialized microvili on one side that project into ____ and the other side has processes of ___
- endolymph
- CN VIII
hair cell microvilli are known as _____ and are arranged in graduated rows with the _____ toward one side
- sterocilia
- tallest
____ are located near the tallest stereo cilia in semilunar ducts, utricle, and ____
- kinocilium
- saccule
____ hair cells lack kinocilia
cochlear
the tips of ____ and tallest stereo cilia are embedded in specialized mass of gelatinous material
kinocilium
concerning hair cells, movement of gelatinous mass relative to hair cells causes ____ of stereo cilia and a ____ ____ is transduced
- deflection
- receptor potential
deflection towards tallest stereo cilia ____ hair cells
DEpolarizes
deflection away from tallest stereocilia _____ hair cells
HYPERpolarizes
deflection of hair cells in ___ ____ has no effect; no receptor potential results
perpendicular plane
outer and middle ears convey airborne ____ ____ to fluid-filled inner ear
sound vibrations
the ____ moves the perilymph
stapes
the fact that the tympanic membrane is 15x the size of the stapes footplate means what?
stapes vibrations have more force/unit area
the ____ m pulls the stapes away from the ___ window of the cochlea, stiffening the ossicular chain
- stapedius
- oval
pulling the stapes can block you own voice which can lead to ____ ___ when speaking during spasms
clicking sounds
the stapedius is innervated by what?
CN VII
the tensor tympani pulls the ____ in toward the middle ear, stiffening the ossicular plane
malleus
pulling the tensor tympani blocks ___ sound and can cause spasm causing ____ at low frequency
- chewing
- tinnitus
the tensor tympani is innervated by what?
CN V
perilymphatic space in the cochlea that is continuous with the vestibule
scala vestibuli
structure of the cochlea that contains endolymph
scala media
perilymphatic space in the cochlea that ends blindly at round window
scala tympani
spongy bone at core, houses spiral ganglion, cells bodies of primary afferent fibers. its fibers collect to form cochlear division of VIII
modiolus
separates the endolymph from the perilymph
reissner’s membrane
strip of cells that rests on basilar membrane composed of inner hair cells and outer hair cells
organ of corti
group of cells of organ of corti that are not attached to gelatinous tectorial membrane and are stimulated by endolymph movement across the stereocilia
INNER hair cells
group of cells of organ of corti that have sterocilia inserted into tectorial membrane and vibrations in basilar membrane causes oscillations in membrane potential of hairs
outer hair cells
stapes movement causes a pressure pulse in ___ ___ that leads to a traveling wave of deformation in the ___ ___
- scala vestibuli
- basilar membrane
___ properties of basilar membrane differ along its length, so a traveling wave reaches peak amplitude at a location that depends on ____ ____
- mechanical
- stimulus frequency
“___ ____” of basilar membrane is the beginning of tonotopic organization of auditory system
mechanical tuning
particular frequencies are mapped to specific locations of ___ ___ and ____
- relay nuclei
- cortex
machine that takes advantage of tonotopic organization of cochlea in which you place electrodes in ROUND window into scala tympani so different electrodes are placed at different points along the basilar membrane to stimulate CN VIII
cochlear implant
when can you use a cochlear implant
when cochlear hair cells are damaged but the VIII endings are still intact
CNS auditory processing analyzes what two things?
- sound frequency
- intensity
the ____ ___ is the primary ascending auditory pathway in that it carries info from ____ ____
- lateral lemniscus
- both ears
the lateral lemniscus mostly consists of fibers from ___ ___ nucleus
dorsal cochlear
where is the primary auditory cortex located?
transverse temporal gyri of Heschl on superior surface of temporal lobe
unlike other temporal gyri, the gyri of the primary auditory cortex run ______
medioloaterally
what important structure is located in the primary auditory cortex?
brodmann areas 41 and 42
the CNS auditory processing can compare what two things?
- arrival time
- intensity
*allows you to know that sound in your left ear means that something is on you left side
the superior olivary nucleus is important to ____ ____
sound localization
the superior olivary nucleus receives fibers form ___ ___ ___ and they cross midline through ____ ____
- bilateral cochlear nucleus
- trapezoid body
what are the two sub nuclei to the superior olivary nucleus
- medial
- lateral
plot of data that measures subject’s threshold hearing for a series of pure tones through earphones (air conduction) and vibration (bone conduction)
audiogram
process of audiogram that prevents sound from reaching labyrinth
conductive hearing loss
process of audiogram that may damage hair cells or cochlear nuclei
sensorineural hearing loss
regarding audiograms, they compare results from testing ___ and ___ conduction
- air
- bone
air conduction needs what three things to be intact?
- outer
- middle
- inner
regarding audiograms, ____ ____ bypasses ear as skull can transmit sound waves to fluids in labyrinth
bone conduction
normal hearing by bone conduction but not by air suggests a ____ ___ ____
conductive hearing loss (middle ear infections)
the vestibular division of VIII detects what two things?
- linear acceleration
- angular acceleration
the vestibular division of VIII regulates ____ and coordinates ___ and ____ movements
- posture
- eye
- head
semicircular ducts, urticle, saccule are _____ in bony labyrinth rather than ___ like the cochlear duct
- suspended
- stretched
receptors in semicircular ducts detect ___acceleration of the head
angular
each semicircular duct communicates at BOTH ends with the ____
utricle
one end of each semicircular duct has an ___ that contains ___
- ampulla
- crista
concerning semicircular ducts, transverely oriented ridge with hair cells
crista
concerning semicircular ducts, sterocilia in gelatinous mass
cupula
the ____ covers the crista and extends across ____
- cupula
- ampulla
all hair cells are aligned so ____ face in the same direction
kinocilia
concerning semicircular ducts, deflection of ____ in one direction leads to ____ firing in afferent fibers
- cupula
- increased
what process leads to rotation of the semicircular duct in an axis perpendicular to it
deflection of cupula
as rotation of the semicircular duct begins ____ lags behind due to ____ and deflects cupola stimulating hair cells
- endolymph
- inertia
if rotation of semicircular ducts is maintained the endolypmh will do what?
catch up (will not be detected, no big deal)
when rotation of the semicircular ducts stops, the ____ keeps moving
endolymph
____ and ____ receptors detect linear acceleration of the head
- utricle
- saccule
the utricle and saccule each contain a patch called a ____
macula
the macula of the utricle is ____ when the head is upright
horizontal
*sterocilia face up
the macula of the saccule is ____ when head is upright
vertical
*sterocilia face laterally
the utricle detects what types of movement?
- forward-backward
- side-to-side
the saccule detects what types of movement?
- forward-backward
- up-down
what makes the otolithic membrane denser than endolymph?
calcium carbonate crystals (otoliths)
what are the four vestibular nuclei inputs?
- inferior
- medial
- lateral
- superior
each semicircular duct and macula has its own pattern of termination in the ___ ____
vestibular nuclei
the vestibular projections include the CEREBELLUM and SPINAL CORD, as well as nuclei of what three CNs
- III
- IV
- VI
the vestibular nuclei are _____
contralateral
the vestibular projection of the thalamus to cerebral cortex provides conscious awareness of ____ ___ ___
movement in space
what are the two contributions of vestibular projections to VISCERAL nuclei?
- adjusting cardiovascular system for lying down-standing up
- seasickness
the lateral vestibulospinal tract arises from ____ ___ down ___ ___
- lateral nucleus
- lateral funiculus
concerning the vestibulospinal tract, the excitatory projections go _____ to antigravity mm
ipsiaterally
the lateral vestibulospinal tract mediates ____ changes to accommodate tilts in body
postural
the medial vestibulospinal tract arises form ___ ___ and extends to ____ ___ via MLF
- medial nucleus
- cervical cord
the _____ vestibulospinal tract stabilizes head movement as we walk
medial
the medial vestibulospinal tract also coordinated ___ and ___ movements
- head
- eye
the _____ reflex is the vestibular system working to prevent images from moving on the retina
vestibuloocular reflex
what is the afferent limb of the vestibuloocular reflex?
CN VIII (vestibular division)
what are the three efferent limbs of the vestibuloocular reflex
- III
- IV
- VI
what are the interneuronal connections in the vestibuloocular reflex?
vestibular nuclei to MLF to III, IV, VI and reticular formation
if the vestibuloocular reflex cannot compensate for head movements, it is interrupted by very rapid eye movements in the opposite direction
nystagmus
*if you are on a train watching telephone poles go by
____ makes the copula sensitive to gravity
alcohol
*see slide 52 for more info on this
position sense is mediated by what three system working together to produce sense of orientation and movement
- vestibular
- propiroceptive
- visual
*if one of these systems is damaged, the others can compensate for it
___ ___ refers to the feeling that you are moving when you look out the window of a stationary train to see another trains moving
position sense
if vestibular function or somatosensory function is lost, ___ can compensate
vision
you can test for position sense by asking patient to close their eyes and see if they sway or loose balance. this is known as ____ ____
romberg’s sign
