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Year 1: 06. Neuro Exam 2 > Lecture 13: Vestibular System > Flashcards

Lecture 13: Vestibular System Flashcards

1
Q

What is the peripheral receptor apparatus responsible for?

A

Transducing head motion/position in the inner ear

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2
Q

What is the central vestibular nuclei responsible for?

A

Integrating and distributing info that controls motor activities and spatial orientation in the brainstem

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3
Q

What is the vestibuloocular network responsible for?

A

Control of eye movements

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4
Q

What is the vestibulospinal network responsible for?

A

Coordinates head movements, axial musculature, and postural reflexes

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5
Q

What is the vestibulothalamocortical network responsible for?

A

Conscious perception of movement/spatial orientation

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6
Q

What is the function of semicircular canals?

A

Sense angular accelerations (via rotational head movements)

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7
Q

What are the three semicircular canals?

A

Horizontal
Anterior
Posterior

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8
Q

What is the function of the otolith organs?

A

Sense linear accelerations (via translational head movements)

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9
Q

What are two otolith organs and what do they specifically sense?

A

Utricle: Horizontal linear acceleration
Saccule: Vertical linear acceleration

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10
Q

What innervates receptor cells in vestibular organs?

A

Primary afferent fibers of Vestibular/Scarpa ganglion

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11
Q

Where do the vestibular pathways eventually terminate?

A

Ipsilateral vestibular nuclei and cerebellum

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12
Q

Where is perilymph located?

A

Between membranous and bony labyrinths

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13
Q

What is membranous labyrinth filled with?

A

Endolymph

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14
Q

What is endolymph “bathing?”

A

Auditory and vestibular systems

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15
Q

What does the movement of endolymph allow?

A

Responses in vestibular organs, either excitation or inhibition

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16
Q

What are the vestibular labyrinth organs?

A

Semicircular Canals

Otolith Organs

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17
Q

What supplies the labyrinth structures?

A

Labyrinthine Artery from AICA

Stylomastoid Artery

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18
Q

What can cause Meniere’s Disease?

A

Disruption (increase) of endolymph volume that can lead to endolymphatic hydrops, which is an abnormal distention of membranous labyrinth

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19
Q

What are the symptoms of Meniere’s Disease?

A 
Fluctuating hearing loss
Vertigo
Positional Nystagmus
Nausea
Vomiting
Tinnitus
20
Q

What are some treatments for Meniere’s Disease?

A

Diuretics
Salt-restricted diet
Implantation of a shunt to drain excess endolymph

21
Q

What activates hair cell movement?

A

Endolymph

22
Q

What happens when stereocilia move towards or away from kinocilium?

A

Towards: Depolarize –> activation
Away: Hyperpolarize –> inhibition

23
Q

What structure is found within the semicircular ducts?

A

Ampulla that extends into cupula

24
Q

Where are hair cells found in semicircular ducts?

A

Embedded in cristae (base of ampulla)

25
Q

What structure is found in the otolith organs?

A

Macula

26
Q

How do hair cells in the macula receive input?

A

Otoconia on the otolith membrane will move depending on head movement, bending hair cells underneath

27
Q

How is information relayed from the semicircular canals and otolith organs?

A

Primary afferents from the vestibular labyrinth organs form CN VIII and enter at the pontomedullary junction.
CN VIII then synapses to either superior, medial, lateral, and inferior vestibular nuclei.

28
Q

How does the vestibular system send information to the cerebellum?

A

Vestibulocerebellar fibers go through the juxtarestiform body in the inferior cerebellar peduncle

29
Q

What is the function of cerebellovestibular fibers?

A

Regulatory Mechanisms for eye and head movements + posture

30
Q

What is subjective vertigo?

A

Patient experiences spinning sensation

31
Q

What is objective vertigo?

A

Objects are spinning and patient is still

32
Q

What is benign paroxysmal positional vertigo?

A

Brief episodes of vertigo that coincide with particular changes in body position

33
Q

What can cause cupulolithiasis?

A

Otoconial crystals from utricle separate and get lodged in cupula of semicircular canal

34
Q

What is a vestibular schwannoma?

A

Benign tumor from Schwann cells of vestibular root that impinges on structures traversing the internal acoustic meatus

35
Q

What is vestibular neuritis?

A

Inflammation of vestibular nerve that can cause vertigo, nausea, and vomiting but not hearing loss

36
Q

Where does the lateral vestibulospinal tract arise from?

A

Lateral and Inferior vestibular nuclei

37
Q

What is the function of lateral vestibulospinal tract ?

A

Powerful control over extensors for maintenance of posture

38
Q

Where does the medial vestibulospinal tract arise from?

A

Medial vestibular nucleus

39
Q

What is the function of medial vestibulospinal tract ?

A

Stabilizes head via activation of neck musculature

40
Q

Where do all vestibular nuclei project to?

A

Ventral posterior nuclear complex

41
Q

What is the specific function of the vestibuloocular reflex?

A

Stabilizes retinal images during head movements

42
Q

How does the vestibuloocular reflex work?

A

Movement in the semicircular ducts activate vestibular nuclei that stimulate the lateral and medial rectus muscles

43
Q

If you are focusing on an object and turn your head to the left? Which CN nuclei are activated? What is inhibited?

A

Activated: Ipsilateral CN III (oculomotor), contralateral abducens

Inhibited: Ipsilateral abducens N.

44
Q

Describe the two phases of nystagmus.

A

Slow phase: Vestibuloocular reflex directs eyes slowly in direction opposite to head motion

Fast phase: Eyes rapidly spring back to central position to the same direction as the head

(Named for direction of fast phase)

45
Q

How is the caloric test performed?

What is a normal result?

A

Warm water: Nystagmus beats toward ear which warm water was poured

Cold water: Nystagmus beats away from cold water

Should be equal bilaterally

46
Q

What is an abnormal result of a caloric test?

A

Reduced/absent nystagmus ipsilaterally

47
Q

An unresponsive patient arrives in the ED. In order to evaluate the condition of the brainstem, you perform a Doll’s Eyes maneuver. What result would indicate that the patient’s brainstem was intact? What part of the brainstem?

A

Pt’s eyes move in opposite direction of the head turn

Reticular formation intact

Year 1: 06. Neuro Exam 2 (28 decks)

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