Neuro 44 45 Vestibular System

Front 1

what are 3 things that the vestibular system does

Back 1

1. Sense head movement

2. keep eyes on target when head is moving

3. Lets limbs/trunk be balanced when head is moving

Front 2

what system senses head movements

Back 2

vestibular

primary fx is to sense head movements. it tehn takes this ingo and focuses the eyes to keep the head balanced

Front 3

what system lets you keep your eyes focused on an object while your head is moving

Back 3

vestibular

Front 4

what system lets you limbs/trunk stay balanced even when you head moves

Back 4

vestibular

**keep in mind that head movemnts lead other movements

Front 5

what is the main job if the vestibular system

Back 5

sensing movments of head in relation to what the eyes are viewing and what movements the rest of the body is doing

Front 6

the input from the vestibular system controls wht

Back 6

Extraoccular mm- keep eyes on target while head moves

Paravertebral and limb mm- main tain balance

Front 7

what are the efferents of the vestibular system (2)

Back 7

1. Extraoccular mm to keep eyes on target as head moves

2. paravertebral and limb mm to maintain balamce

Front 8

what is the main overview of the vestibular pathway

Back 8

1. Vestibular sesnory apparatus

2. CN VIII to the vestibular nuclei

3. From vestibular nuclei it branches and a SMALL portion goes to cortex, the majority goes to the lateral vistibulospinal tract to connect the tract to mm for balance, Another part ascending in the MLF to reach the motor nuclei of CN 3 4 6.

Front 9

so the vestibular system is a sensory system how is different than the other sensory paths we learned

Back 9

its main job is not to jsut relay the sensory info, its main job is to deliver the info and then convert it to motor output for 1 reflexes and 2. voluntary movemnts

Front 10

so we know sensory info comes in from the vestibular sensory appratus nad then travels in CN VIII to the vestibular nuclei, from here what are the projections

Back 10

1. lateral Vestibulospinal tract, (descending MLF) located throughout the entire length of the SC to control mm of head neck trunk and maintain balance when head moves

2. Some ascends in the MLF to enter the motor nuclei of 3 4 6 to control extraoccular eyemovemnts while the head is moving

3. a SMALL portion goes to the thalamus nad hten to the cortex to relay the sensory info

Front 11

from the vestibular nuclei what does the ascending info do? descending

Back 11

Ascending: MLF enters motor nuclei 3 4 6 to control extracoccular eye mm while head is moving (keep eye on target)

Descending: lateral vestibulospinal tract (descending mlf) to control head, neck, trunk to maintain balance whille head is moving

Front 12

what does dizzyness refer to? how does it compare to vertigo

Back 12

Dizzy: loss of balance, spatial disorientation

vertigo: sensation of spinning WHEN NO MOVEMENT IS TAKING PLACE

Front 13

is there movemnt associated with vertigo or dixxy

Back 13

dizzy

**in vertigo it refers to spinning sensation WITH NO MOVEMENT takign place

*dizzy is spatial disorientation or loss of balance with movemnt

Front 14

what is menieres disease

Back 14

when you cent remove/recycle endolymph and so the build up causes vertigo and hearing loss

Front 15

what happens when the endolymoh is not properly recycled

Back 15

meinieres disease
**recurrent episodes of vertigo (spinning w/o movement) and hearing loss

Front 16

what is acoustic neuroma

Back 16

tumor of schwann cell involvving CN VIII btwn the brainstem and Internal acoustic meatus (where CN VIII nad VII enter)

Front 17

waht it is called when you have a schwann cell tumor

Back 17

acoustic neuroma

**the CN VIII is compressed bten brainstem and internal acousitc meatus. can also affect CN VII

Front 18

what are the names of the semicircular dicts in the vestibular system? what are they full of? what is their fx

Back 18

Anteriro
lateral/hormizontal
Posterior

**they are full of endo lymph and serve as the vestibular receptors (there are a total of 5 receptors, theise 3 and then the utricle and saccule)

Front 19

what is the orientation of the saccule? utricle?

Back 19

saccule: vertical

utricle: horizontal

Front 20

so we know the cochlea is made of interconnected membranes surrounded by bony canals, is this true of hte vestibular system

Back 20

yep

Bony labrynith (canal)
membranous labrynith (duct)

**the endo and periymph are connected as well!

Front 21

what macule is horizontal? what is verticle?

Back 21

horizontal: utricle

verticle: saccule

Front 22

what part of cochlea is full of endo? what is it continuous with in the vestibular system? where is endolymph made

Back 22

cochlear duct

**continuous with the saccule, utricle, and 3 semicircular ducts.

**made from stria vascularis (high K, low Na)

Front 23

wht makes endo? what reabs it?

Back 23

endo made by stria vescularis, reabs by endolymphatic duct

**meniere disease when endo is not properly reabs. Recurrent Vertigo and hearing loss

High K, Low Na in endo

Front 24

what are the 5 vestibular receptors

Back 24

ant, post, horizontal semicircles

utricle
saccule

Front 25

where do the semicircular ducts empty into/what are they connected to

Back 25

utricle

Front 26

how do they think endo is recycled

Back 26

in the subarachnoid space, CSF. mechanism is unknown

**when endo isnt reabs we get meisners

Front 27

what fluid has high K, what has high Na?

Back 27

High K:endo

High Na: peri

**endo is in the cochlear duct nad the vestibular receptors. these atructures are then surrounded in teh high na perilymph (peri=around)

Front 28

so we know the vestibular sensory apparatus (scarpas, vestibular ganglion)is made of 5 parts

what do the semicurcular respond to
what does utricle respond to
what does saccule respond to

Back 28

SemiCircular: christa, rotation of hte head

Utricle: macula, horizontally oriented, responds to horizontal linear head movments

Saccule: macula, oriented vertically, responds to vertical linear had movemnt

Front 29

what vestibular receptor responds to...

horizontal head movement
vertical head movement
rotation of the head

Back 29

horizontal: utricle (macula)
Verticle: saccule (macula)
Rotation: semicircular ducts (christa)

Front 30

is the horizontal semicurcular duct truely hormizontal

Back 30

nope its tilted up about 30*

Front 31

what semicircular dicts work in opposition to one another?

Back 31

the ant on one side is in opposition to the post one one the other

horizontal on each side also work in opposition to each other

**sense rotational movemnt

Front 32

what is the name of the sensory part of the semicurcular ducts? describe all of the part os the anatomy

Back 32

christa

in the duct there is a swelling, ampulla

in the ampula there is an area of specialized epithelium called the christa

there are hair follicles in the christa

the hair follicles project up toward the cupula

the cupula is a gelatinous structure that is anchored to that endo can displace it but NOT move past it

nerve fibers project downward from teh christa/hair cells

Front 33

what systen has kinocilium, what is it

Back 33

vestibular

its the tallest "stereocilium" when directed toward hte kinocilium depolarization, away is hyperpolarization

**cilium w/o the central doublets

Front 34

what is the ampulla, christa and cupula

Back 34

the ampulla is a swelling in the semicircular ducts where sensory transduction occurs

**the christa is the epithelium in the ampula where the hair cells reside

**the cupula is a gelatinous membrane that spans the ampulla. endo can displace it but cant move past it

**sensory receptor in the semicurcular ducts

Front 35

tell me about the type I and II hair cells in semicircular ducts

Back 35

I: totally surrounded by nerve caylex. nerve impulse can be conducted all the way around this cell

II: smaller area for synapse

**both have kinocilium\
**both have the SAME orientation in a single duct, the CL will have the mirror image orientation

Front 36

the kinocilium and stereocilia of the hair cells in semicircular ducts are bathed in what?

Back 36

endo (high K)

the cell body below the cilium is bathed in perilymph (high Na)

Front 37

where are the CN VIII afferents in relation to the ampulla/christa/hair cells in the semicircular ducts

Back 37

they collect below the christa and leave as vestibular afferents towatds the vestibular nuclei

Front 38

what is the orienttaion of the kinocilium in CL semicircular ducts

Back 38

they are mirror images

**opposite and so have opposite responses to movement

Front 39

are their type I and II hair cells located in the same ampulla of a semicurcular duct

Back 39

????? i think so

Front 40

what are the otolithic organs?

Back 40

saccule (vertically)
utricle (horizontally oriented)

Front 41

what is the larger otolithic organs

Back 41

the utricle is larger than the saccule

*the 3 circle ducts lead to the utricle

Front 42

what is hte direction of depolarization of the macula of the saccule

Back 42

<-- I -->
<---I -->
<-- I -->

points away from the striola

**in the maccule of the utricle it points toward

Front 43

what is the stiola

Back 43

in the otolithic organs its on the surface of the maccule and is the place where the kinocilium change directions

Front 44

what is the change in kinoclilum orientation of the scircle ducts nad hte otolithic organs

Back 44

Ducts, CL duct has opposite orientation

Otolithic: at the striola the orientation changes
saccule points awaw
utricle points towards

Front 45

what is the analogous structure to the coupula

Back 45

in the saccule and utricle there is an otolithic membrane, gelatinous and has hair cells in it

Front 46

what is the analogous structure to the christa

Back 46

the saccule. its where the hair cells are located so they can interact with teh otolitis membrane

Front 47

what is otoconia

Back 47

stones in the otolitic membrane, they help to keep the gelatinous otolitic membrane from slipping

Front 48

what organ has the depolarization pointing toward the striola, what points away

Back 48

toward: utricle, horizontal

away: saccule, verticle

Front 49

what is the...

otolithic membrane
otoconia
macula
striola
afferent fibers to brain

**note all of the listed structures refer to the utricle and saccule. list an analogous structure when applicable

Back 49

otolithic membrane: like the coupula. is displaced by endo movement, important in transduction

otoconia: stones in the otolithic membrane that keeps the membrane from moving

macula: like the christa, where the hair cells attach

strolia: where the kinocilium change positions. in saccule they depolarize pointing away. in utricle they depolarize pointing towards (change in position of kinocilium in circular duct occurs in CL ducts)

afferet fibers to the brain: in both the dicts and otolithic organs they leave via hair cells and go to vestibular nucleus

Front 50

if the cupula is displaced toward the kinocilium what happens? what about if its away

Back 50

towads: depolarization,

away: hyperpolarization

**keep in mind that one side (of head or striola) will be depol and the other is hypoerpol

**when the endo moves toward K channels open and this willd epolarize the cell

Front 51

what happens when endo is displaced toward the kinocilium

Back 51

mechanically gated K channels are opened and K enters the cell

**the sterocilia are bathed in endo which is high in K. the cell bodies are bathed in peri which is high in na

Front 52

when the head rotates to the left what way does endo move?
what happnes to depolarization/hyper?
what mm engage

Back 52

endo moves to right, will depolarize L side and hyperpolarizew R side

the L medial rectus and R lateral rectus engage to keep eyes on center

Front 53

otolithic organs sense what type of movemnt? what about the circle ducts

Back 53

linear acceleration, side to side, up/down

ducts are rotation

Front 54

if you walk on a flat surface what part of the vestibular system sense it? what about an elevatoe

Back 54

walk on ground: side to side, utricle

elevator: up and down, saccule

Front 55

what are the steps of signal transduction

Back 55

1. mechanically gated K channels are opened when deflected toward the kinoclium

2, K rushes into the cell and depolarizes the cel (K comes from the endo that bathes the stereocillia)

3. Depolarization leads to increased Ca

4. Ca makes NT release


5. Increased AP in cn VIII

6. cell repolarizes as Ca activated K channels in basal curface and K efflux occurs

Front 56

what happens in kinicilium in horizontal duct is deflected medially, laterally

Back 56

medially: depolarize

laterally: hyperpolarize

Front 57

what is the mech when the endo deflects away from kinocilium

Back 57

1, K channels in sterocilia close

2. cell is hyoerpolarized

3. Ca is decreased, NT release is decreased, AP in cn VIII is decreased

Front 58

so the hair cells in otolithic organs are located where

what is the stroila

waht are otoconia

Back 58

in the macula

striola, seperate kinocilium orientation (towards striola in utricle, away from in saccule)

otoconis are CaCarbonate stones in otolithic membrane

Otolothic membrane detects deflection

Front 59

if deflection happens toward striola and we depolarize where are we

if defelction happens toward striole and we hyperpolarize where are we

Back 59

utricle

saccule

**saccule is verticle and points away

**utricle is horizontal and ponts towards

Front 60

how many vestibular nuclei are there? what are they called? what info enters them

Back 60

4
superior
lateral
medial
inferior

they receive info from CN VIII from the otolithic organs nad hte semicircular canals (also commissural fibers, cerebellum, and SC)

Front 61

in what part of the brainstem are the vestibular nuclei

Back 61

superior and lateral and the tip of medial are in the pons

the inferiror and hte bulk of hte medial are in the medulla

Front 62

what are the afferents into the vestibular nuclei

Back 62

1. CN VIII
2. Cerebellum
3. Commissure Fibers
4. Spinal Cord (proprioception)

Front 63

what are the efferents of the vestibular nuclei (5)

Back 63

1 MLF (ascending and descending)
2. COmmissural Fibers
3. Vestibulospinal tract
4. Vestibulo-Cerebellar fibers (including primary CN VIII fibers that go directly into the cerebellum, and 2 vestibular nuclei axons to the cerebellum)
5. Vestibulo-Thalamo-Cortical: vestibular nuclei to VPL of thalamus then goes to area 3a (base of central sulcus near hte face region of postcentral gyrus) area 2v (base of intraparietal sulcus just post to hand/mouth region in post central gyrus)

Front 64

what are the effernts from the vestibular nuclei to the cerebellum

Back 64

1. Primary: CN VIII that go directly into the cerebellum

2. Secondary: vestibular nuclei axons to cerebellum

Front 65

if we can see restiform body what vestibular nucleus are we looking at

Back 65

inferior

**when the ICP is connected to the cerebellum we are looking at the lateral vestibular nucleus

Front 66

when are we looking at inf or lateral vestibular nucleus

Back 66

inthe rostral medulla there is the restiform body and so its inferior

when we see the ICP connected to the cerebellum it is lateral (more superior)

Front 67

where do we see the medial and inferiore vestibular nuclei

Back 67

at the level of the rostral medulla. we can see the restiform body not connected as the ICP

**the medial is more medial and homogenous looking
*inferior is more lateral, right next to the lateral side of the restiform body. more speckled looking

**bother are at the postero mid side

**cochlear are at this level but are more lateral

Front 68

ok so what vestibular nuclei do we see at the medulla/pons transition? what dose this area look like

Back 68

on cross section it looks like pons and we see all 3 cerebellar peduncle (this clues us that we see lateral and not inferior vestibular nuclei)

**at this level we see a homogenous nucleus medially, this is the medial vestibular nucleus

**then more laterally we see a speckeled nucleus, this is the lateral (if we go superior to midbrain its superior, and inf to medulla its inferior)

Front 69

at what level do we see the medual, superior, and lateral vestibular niuclei all in the same cross section

Back 69

caudal pons

the sup is most post
the medial is homogenous and medial
the lateral is lateral and looks more speckled

Front 70

what are the excitatory inputs into the vestibular nuclei? what about inhibitory

Back 70

1. CN VIII
2. Commissural Fibers
3. Cerebellar Fibers
4. Spinal cord

the only inhibitory is the cerebellar (note the cerebellar are + and -)

its the flocculonodular lobe

Front 71

what is the afferent into the vestibular nuclei that can be excitatory OR inhibitry

Back 71

cerebellar

From fastigial nucleus is excitatory

From PKJ cells its inhibitory

from the flocculonodular lobe

Front 72

what is the input into the vestibular nuclei that lets the R side know wht the L is doing

Back 72

commissural fibers

Front 73

describe the input into the vestibular nuclei that came from teh vestibular (scarpas ganglion)

Back 73

well its the CN VIII info

the sensory from the otolithic and semicurcular ducts travel inCN VIII to get to the vestibular nuclei

the vestibular gang houses the cell bodies of the fibers that came from teh otolithic and semicurcular ducts

Front 74

what carries info from the mm spindles into the vestibular nuclei

Back 74

the spinal cord (spinocerebellar afferents)

Front 75

so we know the MLF is an afferent/efferent of hte vestibular nucleus

what specifically does the ascending and descending MLF do

Back 75

EFFERNT

Ascednign: control extraoccular mm

Descedning: control limb mm

Front 76

we are commissural fibers effernt or afferent

Back 76

BOTH! they let the sides talk so what is affernt is effernt to the other side

**these let the R and L vestibular nuclei talks

Front 77

what is another name for the descending MLF what info does it have

Back 77

medial vestibulospinal tract

**effernt info from vestibular nuclei to control limb mm

Front 78

what are hte vestibulospinal effenrts form teh vestibular nuclei

Back 78

lateral vestibular
medial vestibular (descending MLF)

control mm of neck, trunk, UE, LE

Front 79

what is the relation of the vestibulo-cerebellar projections and the vestibular system

Back 79

vestibulo-cerebellar is an effernt for vestibular system

includes:
1. Primary fibers: vestiular receptors from CN VIII directly to cerebellum
2. Secondary: vestibular nuclei axons to cerebellum

Front 80

what is the cortical efferents from the vestibular system? where are the projections to in the cortex (2)

Back 80

1. 3a: postcentral g near the head

2. 2v: base of intraparietal sulcus just post to the hand/mouth region in postcentral g

Front 81

what is teh VOR (vestibulo ocular reflex)

Back 81

if your eyes are fixed on an object adn you rotate your head your eyes will rotate in the CL direction

Front 82

what is the reflex that makes your eyes move CL to head rotation if your eyes are fixed on an object

Back 82

VOR

vestibulo-ocular reflex

BOTH eyes look CL, conjugate movemnt of eyes

Front 83

what is the orientationof kinocliium of the horizontal semicircular ducts

Back 83

the kinocilium is medial

**mirror images, tallest medially and then they are shorter

**this has the effect of one being depolarized nad the other being hyperpolarized for a given movement bc the endo moves the same way in both

Front 84

when the head moves L, what direction do the eyes move? what direction does endo move, what effect does this have (depol/hyperpol)? what mm are moved

Back 84

when the head rotates L the eyes move R

**the endo moves R, this will depolarize the L duct and hyperpolarize the R duct

**to get hte eyes to move R the R lateral Rectus (oculomotor) and hte L medial rectus need to fire (abducens)

**the kinocilium is tallest medially

Front 85

what is the cutesy thing that tells us what eye mm are innervated by what CN

Back 85

SO4 LR6 AO3

Front 86

what mm fire to make the eyes move Left (head moves R)

Back 86

L lateral Rectua
R medial Rectus

Front 87

when the head rotates L what way does the endo move

Back 87

R

**its like the rotation drives fluid into the cupula

Front 88

if the R lateral Rectus and the L medial Rectus fire what direction are the eyes movein? what way must the head have rotated? what way must have the endo rotated

Back 88

eyes look R
Head moves L
Endo moves R

Front 89

so in VOR the head and eyes move CL, what direction does hte endo move

Back 89

same direction as the eyes! so CL to head rotation

Front 90

what is the path of the VOR

pretend that the head rotated to the L

Back 90

1. L vestibular nucleus is activated

2. from L vestibular fibers ascend in the R MLF and synapse in R abducens

3. From R Abducens 2 things happen. 1. R lateral rectus fires. 2. Fibers project across midline to L MLF nad go to occulomotor nucleus

4. From R ovvulomotor the R medial rectus is fired

5. BOTH eyes stim to look R as the head moves L

Front 91

what nuclei are involved in teh VOR

Back 91

1. Vestibular: 1 nucleus is activated depending on what way the head rotates (whn rotated L, the L is activated)

2. Abducens: the CL abducens activales the lateral rectus on that side

3. Occulomotor: now we are back to the original side. Axons here innervate the medial recuts

Front 92

what is VOR named for

Back 92

the direction of EYE movement

a L head rotation makes eyes move R so its a R VOR

Front 93

what way does the head move in a L VOR

Back 93

head moved R, eyes move L

*VOR is names foe EYE movement

Front 94

what is nystagmous

Back 94

alternating slow and fast movements

named for direction of FAST movement

Front 95

nystagmous is named for what

Back 95

direction of FAST movement

*nystagmous is alternating slow and fast eye movemnts

Front 96

are the eye movements of nystagmous conjegate or non?

Back 96

conjugate

**eyes move in same direction

Front 97

what controls the SLOW component of nystagmous? fast

Back 97

SLOW: vestibular nuclei efferents to abducens

FAST: not understood

Front 98

the output from vestibular nuclei to the abducens nucleus causes what part of nystagmous

Back 98

slow phase

Front 99

what does nystagmous indicate

Back 99

a pt has a leision in the vestibular circuts or CN VIII

Front 100

what manifests as a lesion to brianstem vestubular circuits or CN VIII damage

Back 100

nystagmous

Front 101

can nystagmous ever be a good ting!

Back 101

sure is, when clinician induces it!!

**if your out and nystagmous is induceable we know you dont have leision in vestibular circuiuts or CN VIII

Front 102

with a leision on the R what kind of nystagmous do we have

Back 102

to the L

**L is determined by fast movment


**slow movemnt is controlled by vestibular nuceli output to the abducens nucleus. so eyes move slowely to the R

Front 103

if you ahve a leision on the L what way is the nystagmous

Back 103

to the R

Front 104

waht does COWS mean

Back 104

Cold water in the L ear makes R nystagmous

Warm water in L ear makes L nystagmous

**the side of leision is same as the cold water.

Front 105

what does warm water in the ear do? cold?

Back 105

warm: rises endo and the IL ear is depolarized (prodices nystagmous on same side that the water is in)

Cold: causes endo to sink and HYPERPOLARIZe the IL receptor (Cold makes nystagmous in the opposite ear, leision is same as cold water)

Front 106

if we have a leision on the R what happens to nystagmous

Back 106

L beating Nystagmous

water in the R ear does same thing.

Front 107

what is caloric stimulation

Back 107

putting water in someones ear to induce nystagmous. NORMAL

**warm water in L ear makes L bystagmous (rises the endo and leads to depolarization)

**cold water in L ear makes R nystagmous (sinks endo and causes hypeepolarization)

Front 108

so in terms of cold and warm water and leision what 2 things give same deal

Back 108

Leision and cold water

a R leision or cold water in the R ear will BOTH cause L nystagmous