Neuro-Vestibular System

Question 0

membranous labyrinth

Answer 0

membrane-lined cavities inside of the bony labyrinth

Question 1

vestibular aqueduct

Answer 1

connects semicircular canals to inside of the skull

Question 2

vestibule contains

Answer 2

saccule and utricle

Question 3

ampulla

Answer 3

dilated portion of each semicircular duct

where the cristae are located

Question 4

cochlear duct

Answer 4

part of the membranous labyrinth in the cochlea

Question 5

endolympathic duct

Answer 5

passes through the vestibular aqueduct and conveys endolymph to a sac that is closely related to the signmoid sinus inside skull where endolymph is resorbed

Question 6

perilymph

Answer 6

all space outside of the membranes is filled with this

**in communication with CSF through cochlear aqueduct (probably explains deafness associated with meningitis)

Question 7

potential difference between endolymph & perilymph

Answer 7

+80mV

created by pumps in stria vascularis

Question 8

apex vs base of hair cell

Answer 8

apex: in contact with endolymph
base: in contact with perilymph

Question 9

hairs are actually

Answer 9

sterocilia

Question 10

deflection of hairs towards kinocilium

Answer 10

pulls on tip filaments–>opening K channels–>K into hair cell (depol)–> open Ca2+ channels at base of cell–> Ca2+ influx–>NT release and opening of Ca2+ dep K+ channel at base–> efflux of K into perilymph–> repolarization

Question 11

deflection of hair cells away from kinocilium

Answer 11

closes K + channels–>decreased NT release

Question 12

tip filament

Answer 12

motor protein is linked to actin filament in core of stereocilium

Question 13

slow steady release of NT under resting conditions

Answer 13

low intracellular Ca2+–>activate motor protein–> tighten tip filament –>partially open K+ channels –>partially depol–>opens Ca2+ channel

Question 14

2 structural types of receptors in vestibular apparatus

Answer 14

cristea
maculae
**both contain hair cells

Question 15

cristea

Answer 15

located within ampulla of semicircular ducts

–all hairs oriented in one direction

Question 16

maculae

Answer 16

reside within saccule and utricle

–small patches of hair cels that have a somewhat complex, curved, 3d orientation, varies on different parts of macula

Question 17

striola

Answer 17

dividing line running down the middle of this patch

–separates regions of hair cells with different polarity

Question 18

maculae are found

Answer 18

in utriculus and sacculus

Question 19

maculae consist of

Answer 19

hair cells protruding into a gelatinous material studded with calcium carbonate crystals

Question 20

calcium carbonate crystals..

Answer 20

increase the density of the gel, allowing the macular to respond to gravity

Question 21

maculae also detect

Answer 21

linear acceleartion

Question 22

polarization of hair cells in macula

Answer 22

contains hair cells oriented in virtually every plane of head, so tehrefore with any movement of head some hair cells are activated and some are inhibited

Question 23

otoconia/otoliths

Answer 23

calcium carbonate crystals

Question 24

forward acceleration vs deceleration

Answer 24

transient, no head tilt acceleration: they go backwards deceleration: they go forward

Question 25

during constant tilt

Answer 25

firing slowly adapts by decreasing frequency

Question 26

cupula

Answer 26

gelatinous mass that the cristae hair cells project into | no otoliths, so the density is the same as the fluid surrounding it (does NOT detect any gravitational forces)

Question 27

cristae are mostly activated..

Answer 27

by currents within endolymph of semicircular canals | -->deflect cupula-->bend hair cells (currents in one direction excite and in the other inhibit)

Question 28

semicircular ducts

Answer 28

``` organized in 3 planes at right angles to each other angular movements (spinning, pitching, tumbling) result in fluid movement in ducts ``` -->vestibular system integrates the amount of excitation & inhibition of all three cristae within to allow you to detect angular acceleration in any of the three planes (flexion-extension, lateral bending, rotation of head)

Question 29

anterior canal of one ear..

Answer 29

in the same plane as the posterior canal of other ear

Question 30

clockwise head movement

Answer 30

fluid stays behind because of inertia-->bend crista in direction opposite of head movement-->allows to detect angular acceleartion

Question 31

scarpa's ganglion

Answer 31

release of NT from hair cells of macula and cristae produce AP in the peripheral end of sensory axons-->cell bodies are located here these neurons give rise to the vestibular part of the vestibulocochlear nerve-->runs through internal acoustic meatus to medullary-pontine junction

Question 32

central projections of vestibular afferents

Answer 32

cell bodies-->vestibular ganglion-->axons to vestibular complex of nuclei in dorsolateral aspect of rostral medulla and caudal pons AND flocculus & nodulus

Question 33

8th cranial nerve also has branches//

Answer 33

directly enter cerebellum and terminate in flocculonodular lobe

Question 34

flocculonodular lobe is called

Answer 34

vestibulocerebellum

Question 35

vestibulo-occular reflex

Answer 35

stabilizes eye | projectsion from vestibular nuclei, passes through MLF to nuclei of nerves that regulate eye movement (iii, iv, vi)

Question 36

vestibular righting reflex

Answer 36

vestibular nuclei send projection that descends through medulla towards spinal cord-->medial and lateral vestibulospinal tracts-->body muscle in response to vestibular stimuli

Question 37

other inputs to vestibular nuclei

Answer 37

cerebellum | spinal cord

Question 38

cerebellum input to vestibular nuclei

Answer 38

mostly flocculus and fastigial nucleus adjusts gain of vestibular system -->important in VOR reflex

Question 39

Spinal cord input to vestibular nuclei

Answer 39

incorporates proprioception from body (esp from upper neck)

Question 40

projections to reticular formation

Answer 40

autonomic responses-->nausea, vomiting, flushing, sweating in response to intense vestibular stimulation or motion sickness

Question 41

projection to thalamus

Answer 41

relay to part of sensory cortex | perception of movement0-->produces vertigo when there are abnormalities in vestibular system

Question 42

nystagmus

Answer 42

to and from movements of eyes normal when someone is spinning-->when rotate to right, eyes will move left at same rate and when get to end they will dart right and fix on new target