Sfs - Vestibular System

Front 1

How are the semicircular canals oriented? What are the 3 canals? What do they sense?

Back 1

orthogonally (right angles). Horizontal, superior/anterior, posterior.
Head rotations and respond to angular accelerations.

Front 2

Specialized for horizontal linear accelerations

Back 2

Utricle

Front 3

Specialized for vertical linear accelerations

Back 3

Sacculus

Front 4

1. Head around vertical axis.
2. Axis of head nodding yes.
3. Around axis used to laterally bend head.

Back 4

1. Yaw.
2. Pitch
3. Roll

Front 5

Generates compensatory eye movements in resonse to head movements

Back 5

Vestibulo-ocular reflex. Have to go over 2 Hz to lose ability to stay focused.

Front 6

Provides a compensatory mechanism with a very short latency.

Back 6

Vestibular system. Visual system has a much slower latency.

Front 7

Maintain head position despite body movements

Back 7

Vestibulo-colic reflexes

Front 8

Helps maintain our posture if we start to fall over. Most important system for balance. Sends signals mainly to extensor muscles.

Back 8

Vestibulospinal

Front 9

Major players in vestibular system (just like auditory)

Back 9

Hair cells

Front 10

When stereocilia move in direction of the kinocilium, what will happen? What about the opposite direction?

Back 10

It will cause stretch and potassium will flow into the hair cell.
Opposite direction - potassium stops flowing.

Front 11

Swelling at base of each semicircular canal?

Back 11

Ampulla

Front 12

In the ampulla, how are the stereocilia oriented?

Back 12

In a single direction to sense canal rotation. Cilia are connected to a cupula to catch the endolymph as it moves.

Front 13

Dividing component of sacculus and utricle.

Back 13

striola

Front 14

Signaling in sacculus and utricle.

Back 14

Push-pull. Orientation casuses signals to stimulate one group and oppose the other.

Front 15

1. Maximal sensitivity in the sacculus.
2. Maximal sensitivity in the utricle.

Back 15

1. Vertical linear acceleration.
2. Linear accelerations in the horizontal plane.

Front 16

Calcium carbonate crystals and where they reside.

Back 16

Otoconia. Reside in the macula.

Front 17

Two things that can activate the hair cells via otoconia in the sacculus and utricle.

Back 17

Static tilt and rapid acceleration.
Both cause hairs to bend. Vestibular system can actually get confused between the two and give the same signal.

Front 18

How does the body tell the difference between tilt and acceleration?

Back 18

Short, transient effect interpreted more as acceleration while a sustained effect is interpreted as tilt.

Front 19

The hair cells in the sacculus, utricle, and semicircular canals respond to acceleration or deceleration via a __________ relationship.

Back 19

Push-pull.
Stimulating in one direction will increase the firing from the tonic firing already occuring, while stimulation in the opposite direction will cause a decrease in firing rate.

Front 20

In the SC, hair cells send their stereocilia up into what?

Back 20

cupula (spreads across ampulla)

Front 21

Rotation of the head causes fluids within the SC to move and exert force on the cupula. This causes what to be deflected?

Back 21

The stereocilia. Causing an increase/decrease in firing of the vestibular nerve.

Front 22

Tilt head to what to isolate the horizontal canal?

Back 22

30 degrees downward. Also brings utricles into horizontal plane and sacculus into the vertical plane.

Front 23

Right anterior canal is paired in parallel plane with which canal?

Back 23

Left posterior

Front 24

Left anterior canal is paired in parallel plane with which canal?

Back 24

Right posterior

Front 25

Canal pairs point ____ degrees in their respective direction.

Back 25

45

Front 26

Within the pairs, moving in a direction will _________ firing in one, and ________ firing from the other.

Back 26

Increase, decrease. Stupid question, I know.

Front 27

SCs respond to _______, while the signals from the vestibular nerve are related to __________.

Back 27

angular acceleration, head velocity

Front 28

Net effect of turning your head on the semicircular canal system.

Back 28

The cupula is moved, causing the vestibular nerve to send a signal to brain related to head velocity.

Front 29

Why is it important that vestibular nerve records signals related to head velocity?

Back 29

To use head velocity to control eye velocity.

Front 30

Very rapid response, so that despite head moving left/right or up/down, your eyes can stay fixed on an object of interest.

Back 30

Vestibulo-ocular reflex.

Front 31

Caused when vestibular system is in conflict with the visual system.

Back 31

Nausea

Front 32

In the VOR, signals come in from vestibular nerve and go where?

Back 32

To medial vestibular nucleus

Front 33

If head rotates left, signals from the left MVN make _________ connections on the contralateral abducens nucleus and via the MLF make _________ connections on the left oculomotor nucleus.

Back 33

excitatory, excitatory

Front 34

When head rotates left, the left MVN makes _________ connections on the ipsilateral abducens nucleus and via MLF contralateral oculomotor (right) nucleus

Back 34

inhibitory

Front 35

Goal of VOR.

Back 35

Eyes move in opposite direction of the head at an appropriate velocity.

Front 36

Causes ocular nystagmus and dizziness due to the VOR.

Back 36

IF you continue to spin slowly at a constant speed, the fluid in the SCs won't be accelerating and the cupula will return to its natural position. When you stop spinning, the fluid decelerates moving the cupula.

Front 37

VOR handles high frequency stimulation well, but has problems with what?

Back 37

slow, continuous stimluations

Front 38

Primarily influenced by the otolith, utricle, and sacculus. Involved with body tilting and preventing falling over.

Back 38

Lateral vestibulospinal tracts

Front 39

In response to body tiliting there will be activation of what motor neurons?

Back 39

Ipsilateral

Front 40

If you transect above the level of the vestibular nuclei, you will observe what type of rigidity?

Back 40

Decerebrate rigidity in which all extensors of the limmbs are activated to prevent you from falling.

Front 41

Primarily modulate head position. Vestibulo-colic reflex.

Back 41

Medial vestibulospinal tracts. Example is dozing off and waking in class (signal to neck muscles).

Front 42

Does the vestibular system degenerate over time?

Back 42

YES. Elderly are more reliant on visual cues for balance, and have more problems with falls.

Front 43

Cells in the lateral and superior vestibular nuclei relay where? Where do they project after that?

Back 43

Thalamus (VPL). Vestibular cortex (ex. Area 3a - primary sensory cortex, parietal cortex)

Front 44

What area of the cortex involved in the vestibular system helps you remember where other objects are located in relation to your body in space.

Back 44

Parietal cortex

Front 45

Eye movements allowing you to:
1. Look back and forth between tow stationary points.
2. Track a moving object
3. Look at objects at different distances.

Back 45

1. rapid seccadic eye movements
2. smooth pursuit
3. vergence