Vestibular Flashcards
Vestibular-Cochlear systems (what brings them together)
Two separate systems housed in thesameend organ, with the sameperipheral innervation
Vestibular-Cochlear systems are innervated by what
CN 8 - vestibulocochlear
what is the difference between hearing and listening
hearing - accidental, involuntary, effortless
listening - focused, voluntary, intentional
where is the Vestibular cochlear systemanatomically
structures of inner ear - the petrous portion of the temporal bone
how may membrane does the inner ear have
two
out and inner membrane
outer membrane of the inner ear
osseouslabyrinthfilled with perilymphfluid
inner membrane of the inner ear
membranous labyrinthfilled with endolymph
Vestibular apparatus
Cochlea
what is the overall role of the Vestibular system
‘Sense of self-motion’, kinesthesis
vestibular system function
Contributes to our sense of self-motion bydetection of head motion
this info is used tostabilize the eyes for vision
Information about self-motion used for maintenance and recovery of balance (via descendingoutput to spinal cord centers)
Vestibular system’s has a an effect on what systems
visual andproprioceptive
Vestibular system’s impact on vision
Stabilize gaze for accurate vision
Vestibular system’s impact on proprioceptive
Generate limb and neck movements to maintain balance duringvoluntary and externally triggered movements
Expectations/predictions of self-motion related to complexvoluntary actions such as reaching and navigation
Neurosensory hair cells have what projecting from their apical surface
cilia
Multiple stereocilia; one kinocilia
where is the NT release form in a Neurosensory hair cell
base
what causes depolarization in a Neurosensory hair cell
Cilia deflected toward the kinocilia
Depolarize hair cell – increase release ofneurotransmitter, increase firing in afferent
what hyperpolorizes a Neurosensory hair cell
Cilia deflected away from the kinocilia
hyperpolarize hair cell – decreased release oftransmitter, decrease firing in afferent
firing rate of a Neurosensory hair cell
baseline firing rate (always firing this is just subject to change)
what are the otolith organs
Utricle and saccule
membranous sacs within the vestibular apparatus
function of the otolith organs
Static equilibrium, theposition of the headinspace with respect to gravity (head tilt)
Linear acceleration
Linear accelerationof saccule
Vertical direction = saccule
Linear accelerationof utricle
Horizontal direction = utricle
what is a macula
found inside each utricle and saccule
hair cells are enclosed in a gelatinous mass topped by calcium carbonate crystals called otoconia
what happens to the otoconia when you tilt your head
When you tilt you head the rocks move and reflect the gelatinous mass
This will deflect the cilia towards or away from the kino-cilia - effecting the firing rate
how do we get directional sensitivity in the vestibular system
Orientationof thekinocilia
What enables sensitivity in all directions
Positionof hair cells about thestriola
For any tilt or linear acceleration, some cells depolarize, somehyperpolarize, some no change
what information do semicircular canals provide
(three canals) provide information on head turning (angular acceleration)
ampulla
is a dilatation located at one end of the semicircular canal
Haircells on the ampulla; projectcilia into what?
gelatinous mass called the cupula
what is the function of the semicircular canals
angularacceleration, a rate of change
what happens to the cilia when we accelerate
cilia deflected toward kinocilia, and hair cell depolarized; firing in afferent increases
with deceleration what happens to the cilia
cilia deflected away from kinocilia and hair cell hyperpolarized; firing in afferent reduced
with constant velocity what happens to the cilia
no change
the Semicircular canals to sends input to
Medial and superiorvestibular nuclei, (output ofnuclei neurons)
Medial and superiorvestibular nuclei send input to where
output ofnuclei neurons tomediallongitudinalfasiculus (MLF)
Vestibulo-ocular reflexes aim
aim tokeep the visual image stable on the retina
stabilize eyes
Rotationalvestibulo-ocular reflex
with head rotation, eyes moveopposite to head (slow phase); quick reset (fast phase)
Translationalvestibulo-ocular reflex
close objects moving fast, far objects moving slower (train window)
otolithsstabilize eyes for far object
Ocular counter-rolling response reflexes
with head tilt, otolithsstabilize eyes to correct for vertical offset
When you put your head down you eye will roll upward – automatic response
Position-vestibular pause (PVP)
Vestibular nucleus neurons
neurons are primary forreflex
receive regular afferent inputs
transmit information aboutpassive head movement
Floccular target (FTN)
Vestibular nucleus neurons
neurons important to modulate orcalibrate the reflex.
Receive irregular afferent inputs and inputsfrom flocculus of cerebellum
Vestibulospinal reflex’s function
aim to integratevestibular with proprioceptive input for accurate spatial orientation
to assure upright
Vestibular only (VO)neurons
contribute to vestibulospinal tracts
Less involved with head movement and gaze
Cerebellar role in Vestibulo-ocular reflexes
to adapt the reflex;
bothusual vestibular inputs to cerebellum and special visual error signal fromclimbing fiber input to Purkinjecell, resets vestibular nuclei neuron tobe less sensitive to vestibular input - adapts reflex eye movement.
role of the outer ear
‘catches’and transferssound waves
loud sound protection
Tensor tympani muscle tightens tympanicmembrane for loud sound protection
role of the middle ear
sound transformed tovibration
Stapedius muscle pulls stapes out of ovalwindow for sound power protection
inner ear role
pressure waves
Neurosensory unit activated for soundreception and representation in afferentfiring pattern to central targets for hearing
what is the Organ of Corti
a structure in the cochlea of the inner ear which produces nerve impulses in response to sound vibrations.
Organ of Corti location
Located in the cochlea of the inner ear
Located in the cochlea of the inner ear
perilympyh
