Unit 2_Vestibular

Question 1

What do the following describe?

• Monitors and regulates position of head and neck in space
• Monitors and stimulates head and body righting reactions
• Balance reactions
• Eye fixation in space while the head moves

Answer 1

Vestibular Functions

Question 2

Where are the following structures found?

Part of the inner ear

3 canals
- Anterior
- Posterior
- Horizontal

Utricle

Saccule

Answer 2

Vestibular Apparatus

Question 3

What vestibular structure is found on the horizontal plane, fast acceleration in car? Stimulated by movement in a horizontal plane.

Answer 3

Utricle

Question 4

What vestibular structure is found on the vertical plane, elevator acceleration? Includes hair stimulated by movement in vertical plane.

Answer 4

Saccule

Question 5

What vestibular structures contain sensory receptors-hair cells?

• Hair cells sit in Maculae
• Otolothic membranes lie over the maculae
• Calcium carbonate crystals or otoconia are on membrane

Answer 5

Otoliths

Question 6

What vestibular structures are organized to detect tilt of the head, monitor linear acceleration, monitor head position with respect to gravity-static equilibrium?

Answer 6

Saccule and Utricle

Question 7

What can’t the Saccule and Utricle differentiate in a singular plane?

Answer 7

Head tilt / acceleration

Question 8

What does the semicircular canal pick up on?

Answer 8

Head tilt

Question 9

What vestibular structure features bilateral symmetry to help us understand that our head is moving in a 3 dimensional space?

Answer 9

Anterior/Posterior Semicircular canals

Question 10

What are endolymph filled canals that connect to the utricle?

• Widened ends called ampulla
• Crista ampullaris in the ampulla contain hair cell receptors
• Cupula overlies crista ampullaris

Cupula moves when head moves which bend hair cells and fires off action potentials in CNVII
- Sense angular rotational movements of the head
- Sense velocity of the head movements

Answer 10

Semicircular canals

Question 11

What structures in the vestibular labyrinth transduce mechanical stimuli into neural signals?

Answer 11

Hair cells

Question 12

What is the degree of exactness?

Answer 12

Fidelity

Question 13

Difference between sides increases ________ of signal.

Answer 13

Fidelity

Question 14

What is the Vestibular Ocular Reflex Goal?

Answer 14

Keep eyes on target

Question 15

What do the following steps describe?

1. 1st order neurons in Scarpa’s ganglion
2. Peripheral process contact hair cells
3. Central process forms CNVIII
   Join the auditory portion of CNVIII
4. Enter brainstem at pontomedullary junction

Answer 15

Vestibular pathway to brainstem

Question 16

What do the following steps describe?

1. Directly to cerebellum
2. Vestibular nuclei
   - Cerebellum-balance
   - Spinal cord Lateral Vestibulospinal tract (LVS) –postural response
   - Spinal cord Medial Vestibulospinal tract (MVS)-head righting
   - Spinal cord Reticulospinal tract (RST) -balance
   - CN Nuclei for extraocular muscles vestibuloocular reflex (VOR)
   - Cortex-conscious perception of balance
   - ANS and reticular system-nausea etc.
3. Vestibulo-ocular reflex (VOR)
4. Vestibulospinal reflex (VSR)

Answer 16

Vestibular pathway (once it gets to the brainstem)

Question 17

What neuropathology includes the following:

• Normal reflexive response to rotation
• Slow and fast phase
• Can be inhibited
• Pathological if present at rest with minimal stimulation lasts excessively long
• Spontaneous, positional or gaze evoked

Answer 17

Nystagmus

Question 18

What neuropathology is associated with the following symptoms:

Balance dysfunction
Abnormal VOR
Abnormal nystagmus
Nausea
Vertigo

Answer 18

Lesion CNVIII or inner ear or VN

Question 19

What are some vestibular neuropathologies?

Answer 19

Loss of blood supply - Labyrinthine (Internal auditory) arteries

Benign Paroxysmal Positional Vertigo (BPPV)

Meniere’s disease (hearing loss, tinnitus, dizziness, nystagmus, nausea, vertigo)

Motion Sickness

Acoustic Neuroma