06b: Central Vestibular System Flashcards

1
Q

Vestibular, aka (X), ganglion sends axons into CNS that courses medial to (Y) structure(s).

A
X = Scarpa's
Y = cochlear nuclei and ICP
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2
Q

Vestibular axons enter CNS and terminate in which subdivisions of vestibular nucleus?

A

All 4 major subdivisions

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3
Q

List the subdivisions of vestibular nucleus, named based on their location wrt (X).

A

X = cerebellum;

Inferior, superior, medial, lateral

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4
Q

A lesion affecting (X) surface of (Y) brainstem structures is likely to impact vestibular system.

A

X = dorsal;

Y = medulla and pons

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5
Q

Through (X), a subdivision of (Y), the vestibular ganglion, unlike any other sensory system, sends axonal projections directly to (Z).

A
X = juxtarestiform body;
Y = ICP
Z = vestibular cerebellum
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6
Q

The vestibular cerebellum is composed of which region(s)?

A

Flocculo-nodular lobe

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7
Q

Main central projections from vestibular nuclei are to (X).

A

X = SC, cerebellum, oculomotor nuclei

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8
Q

T/F: Some neurons in vestibular nuclei also send axons to thalamus.

A

True

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9
Q

Deiter’s nucleus, aka (X), projects to (Y) via (Z) tract.

A
X = lateral vestibular nucleus;
Y = interneurons/motor neurons along entire length of SC (antigravity muscles)
Z = lateral vestibulospinal tract
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10
Q

Head and trunk tilt to the right. Which side of vestibular system activated?

A

Right

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11
Q

Head and trunk tilt to the right. Which lower-extremity muscles activated on R/L sides by (X) tract?

A

R: Extensors
L: Flexors

X = lateral vestibulo-spinal

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12
Q

Patient walks in with stumbling/falling to L side. You realize it’s due to inability to contract L lower extensors in response to body tilt. Which tract has been (ipsi/contra/bi)-laterally impaired?

A

Ipsilateral Lateral vestibulospinal tract

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13
Q

Vestibulospinal reflexes are coordinated with (X) reflexes. What does each respond to?

A

X = cervicospinal

VS: responds to head tilt
CS: responds to trunk tilt

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14
Q

Vestibular nuclei and (X) tract receive strong (stimulatory/inhibitory) influences from higher brain centers.

A

X = lateral vestibulospinal tract;

Inhibitory

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15
Q

Decerebrate rigidity is characterized by (X) symptoms. Where’s the lesion?

A

X = involuntary overactivity of extensor muscles, including upper body;

BELOW red nucleus, impairing higher brain centers that normally indirectly inhibit extensor muscle tone

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16
Q

Medial vestibular nucleus projects (up/down) to:

A

Up: extraocular motorneurons
Down: neck motorneurons

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17
Q

Medial vestibulospinal tract, aka (X), projects (ipsi/contra/bi)-laterally to which part(s) of SC?

A

X = descending MLF
Bilaterally;

Cervical segments

18
Q

Which tract responsible for vestibulo-colic reflex?

A

Medial vestibulospinal

19
Q

Which tract responsible for vestibulo-ocular reflex?

A

Medial vestibulospinal

20
Q

(X) vestibular nuclei, via (Y), send (ipsi/contra/bi)-lateral projections to oculomotor nuclei of which CN?

A

X = superior and medial;
Y = ascending MLF
Bilateral;

CN 3, 4, 6

21
Q

Vestibulo-ocular reflex: You turn your head left. (R/L) Scarpa’s ganglion excited, thus directly exciting (X).

A

L;

X = L vestibular nuclei

22
Q

Vestibulo-ocular reflex: L vestibular nucleus excited. Where does it project?

A
  1. Excitatory projection (through contralateral MLF) to R abducens nucleus
  2. Inhibitory projection (via inhibitory interneurons, through ipsilateral MLF) to L abducens nucleus
23
Q

Vestibulo-ocular reflex: a L abducens nucleus sends which projections?

A
  1. Excitatory projections to L motor neurons to L lateral rectus
  2. Excitatory projections to excitatory interneurons that cross midline and excite R oculomotor nucleus (thus, R medial rectus)
24
Q

Which specific part of vestibular system sends afferents to vermis of cerebellum?

A

Neurons in VN

25
Q

Which specific part of vestibular system sends afferents directly to flocculo-nodular lobe?

A

Primary sensory afferents (from vestibular ganglia)

26
Q

(X) cells in the vermis and flocculo-nodular lobe send (excitatory/inhibitory) axons to (Y), an output nucleus of the cerebellum.

A

X = purkinje
Inhibitory
Y = fastigial nucleus

27
Q

The fastigial nucleus contributes crossed projection to (X) via (Y).

A
X = VN
Y = uncinate fasciculus
28
Q

The fastigial nucleus contributes uncrossed projection to (X) via (Y).

A
X = VN
Y = juxtarestiform body
29
Q

Major functional output from cerebellum to VN is (excitatory/inhibitory), particularly contributing to modulating (X),

A

Inhibitory;

X = effect of LVST on antigravity muscles

30
Q

Projections from fastigial nucleus to VN is (excitatory/inhibitory).

A

Excitatory

31
Q

Semicircular canals primarily project to which VN?

A

Superior and medial

32
Q

Otolith organs primarily project to which VN?

A

Inferior and lateral

33
Q

Aside from (X) vestibular nucleus, which other brainstem inputs control extensor muscle tone? Star the stimulatory inputs

A

X = lateral*

  1. Pontine* and medullary reticular formation
  2. Red nucleus
34
Q

Decorticate rigidity is characterized by (X) symptoms. Where’s the lesion?

A

X = involuntary overactivity of extensor muscles, except upper body;

ABOVE red nucleus, impairing higher brain centers that normally indirectly inhibit extensor muscle tone

35
Q

(X) tract plays key role in vestibulo-collic reflexes, which cooperate with (Y) reflexes.

A
X = medial vestibulospinal
Y = cervico-collic
36
Q

Vestibulocollic reflex functions to:

A

Stabilize head in space

37
Q

Cervico-collic reflex funcions to:

A

Stabilize head wrt trunk

38
Q

Cat falls, back-first, off chair. First, (head/body) turns due to (X) reflex. Then, (head/body) follows due to (Y) reflex.

A

Head;
X = vestibulo-collic
Body;
Y = cervico-collic

39
Q

Pour cold water into patient’s right ear produces no movement of eyes. Where’s the lesion?

A

Lower brainstem (no VOR reflex)

40
Q

Pour cold water into patient’s left ear. Where do you expect eyes to move?

A

To the left

41
Q

Pour warm water into patient’s right ear. Where do you expect eyes to move?

A

To the left

42
Q

Patient has bilateral MLF lesion, aka (X) condition. You pour warm water into right ear. What results do you expect?

A

Internuclear opthalmegia;

Left eye turns laterally; no movement in right eye