Week 1- Vestibular A&P Review

Question 1

PART 1: PERIPHERAL VESTIBULAR SYSTEM - INTRO AND OTOLITH ORGANS

Answer 1

PART 1: PERIPHERAL VESTIBULAR SYSTEM - INTRO AND OTOLITH ORGANS

Question 2

What are the 3 main roles of the vestibular system?

Answer 2

• Estimates body position and movement.
• Postural control.
• Control eye movements.

Question 3

What is an additional role of the vestibular system?

Answer 3

-Autonomic function and consciousness.

Question 4

• What is pitch?
• What is yaw?
• What is roll?

Answer 4

• Pitch = rotation around y-axis (flexion and extension).
• Yaw = Rotation around z-axis (rotation).
• Roll = Rotation around x-axis (side bending).

-Pitch (singer pitches up and down), Yaw (like naw nodding head no)

Question 5

What structures make up the peripheral vestibular system? (2)

Answer 5

• Vestibular Apparatus (body labyrinth, otolith organs, semi-circular canals)
• CN 8- Vestibular branch

Question 6

What structures make up the central vestibular system? (4)

Answer 6

• Vestibular Nuclei
• Vestibular Tracts
• Vestibulocerebellum
• Vestibular Cortex

Question 7

Which system is mainly responsible for relaying information (velocity and acceleration of head)?

Answer 7

Peripheral Vestibular System

Question 8

What are the (3) primary functions of the peripheral vestibular system?

Answer 8

• Stabilize visual images on the fovea of the retina during head movement allow for clear vision.
• Maintain postural stability, especially during movement of head.
• Provide information for spatial orientation.

Question 9

In the peripheral vestibular system, the ___________ labyrinth is suspended inside the _______ labyrinth and is protected by perilymphatic fluid and supportive connective tissue.

Answer 9

• membranous

- bony

Question 10

What are the 3 main parts of the membranous labyrinth?

Answer 10

• Vestibule
• Semicircular Canals
• Cochlea

Question 11

What are the 2 main otolith organs located in the vestibule?

Answer 11

• Utricle

- Saccule

Question 12

• ________ detects movement in the horizontal plane.

- ________ detects movement in the vertical plane.

Answer 12

• Utricle

- Saccule

Question 13

Within the utricle and saccule there are hair cells known as __________ that detect movement and transduce minute displacements into behaviorally relevant potentials.

Answer 13

-Stereocilia

Question 14

• Movement of stereocilia towards kinocilium = ________.

- Movement of stereocilia away from kinocilium = ________.

Answer 14

• EXCITATORY

- INHIBATORY

Question 15

• The hair cells (stereocilia) are encased in a gelatinous layer (macula) and on top of the hair cells are calcium carbonate crystals called what?
• What does it do?

Answer 15

• Otoconia
• Helps to transmit tiny movements and make the organs more sensitive to movements since they are heavier than the structures below.

Question 16

PART 2: PERIPHERAL VESTIBULAR SYSTEM - SEMICIRCULAR CANALS

Answer 16

PART 2: PERIPHERAL VESTIBULAR SYSTEM - SEMICIRCULAR CANALS

Question 17

What are the (3) semicircular canals?

Answer 17

• Anterior
• Posterior
• Horizontal

Question 18

Semicircular canals are responsible for relaying information about ________ velocity while the otolith organs are responsible for relaying ________ velocity.

Answer 18

• angular

- linear

Question 19

• The semicircular canals are encased in the bony labyrinths and contains a fluid called what?
• What does this fluid do?

Answer 19

• Endolymph

- Head rotation causes movement of endolymph, which then causes movement of hair cells.

Question 20

The ampulla is a bulbous formation at the start or finish of each canal that contains the _______, which houses stereocilia and is sensitive to angular movements only.

Answer 20

-Cupula

Question 21

• SCC hair displacements TOWARDS utricle = _________ cupular displacement
• SCC hair displacement AWAY FROM utricle = _________ cupular displacement

Answer 21

• Utriculopedal
• Utriculofugal

(pedal forwards)

Question 22

Utriculopedal cupular displacement is _________ for the horizontal canal and __________ for the anterior/posterior canal.

Answer 22

• Excitatory

- Inhibitory

Question 23

Utriculofugal cupular displacement is _________ for the anterior/posterior canal and __________ for the horizontal canal.

Answer 23

• Excitatory

- Inhibitory`

Question 24

How are the 6 canals paired?

Answer 24

• Horizontals paired.
• R ant and L post paired.
• L ant and R post paired.

(when one is excited the other is inhibited)

Question 25

PART 3: CENTRAL VESTIBULAR SYSTEM

Answer 25

PART 3: CENTRAL VESTIBULAR SYSTEM

Question 26

What are the 3 vestibular reflexes?

Answer 26

- Vestibulo-Ocular Reflex (VOR) - Vestibulo-Spinal Reflex (VSR) - Vestibulo-Collic Reflex (VCR)

Question 27

- Which reflex stabilizes vision during head motion? - Which reflex stabilizes body during head motion? - Which reflex stabilizes neck during head motion?

Answer 27

- VOR - VSR - VCR

Question 28

- The _________ can send down inhibitory drive when we need our eyes to do something outside VOR? - What is VOR Suppression (VOR Cancellation)?

Answer 28

- Cerebellum | - Ability to follow a moving target with eyes and head moving. (watching a tennis ball)

Question 29

Describe the connection from vestibular to ocular nuclei.

Answer 29

Labyrinth → vestibular nuclei → ascending tracts (cross at MLF) → ocular motor nuclei (III, IV, VI)

Question 30

- If we rotate our head to the left what canal is being excited, which is being inhibited? - If we are compensating with our eye movements what muscles will be excited during L rotation?

Answer 30

- left, right | - L adductor, R abductor

Question 31

What is the purpose of the vestibulospinal reflex (VSR)?

Answer 31

-Generation of compensatory body movements to maintain head and postural stability.

Question 32

What are the (5) steps of the VSR?

Answer 32

- Head tilts to side - Ipsilateral SCC/otolith excitation - ↑ Input from vestibular nerve  vestibular nuclei ipsilaterally - MVST/LVST descending drive to truncal muscles - ↑ Lateral truncal extension ipsilaterally/ ↑ truncal flexion contralaterally

Question 33

What are the (3) cervical reflexes?

Answer 33

- Cervico-Ocular Reflex (COR) - Cervicospinal Reflex (CSR) - Cervicocollic Reflex (CCR)

Question 34

_____ interacts closely with and can supplement VOR under certain circumstances and involves eye movements driven by neck proprioceptors.

Answer 34

-COR

Question 35

_____ can supplement VSR under certain circumstances and involves changes in limb position driven by neck afferent activity.

Answer 35

-CSR

Question 36

_____ helps stabilize head on body and involves afferent input caused by changes in neck position (stretch) → contralateral reflexive contraction of appropriate neck muscles.

Answer 36

-CCR

Question 37

The central vestibular system relies on ________ AND _________ references.

Answer 37

- Internal (vestibular) | - External (visual/somatosensory)

Question 38

What are the (4) main structures of the central vestibular system?

Answer 38

- Vestibular Nuclei (lateral, medial, superior, inferior) - Vestibular Tracts (medial/lateral vestibulospinal, vestibulocerebellar) - Vestibulocerebellum - Vestibular Cortex

Question 39

- ________ vestibulospinal tract is involved in head and body position in space, walking upright, and righting/equilibrium reactions. - ________ vestibulospinal tract is involved in head movements and integrating head and eye movements. - Both travel to neck ________ musculature.

Answer 39

- Lateral - Medial - Extensor

Question 40

Vestibulocerebellum is responsible for postural and gaze stabilization via modulation of VOR and VSR by doing what?

Answer 40

-Suppressing/Cancellation

Question 41

- The ______________ tract is important with intended vs actual movement/error correcting mechanism. - The _________-_________ loop involves adaptation of postural responses based on prior experiences.

Answer 41

- Vestibulocerebellar | - Cerebellar/Cortical loop