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Neuro Exam 2 > 12 Vestibular System and Cerebellum - Β > Flashcards

12 Vestibular System and Cerebellum - Β Flashcards

1
Q

The deep indentations of the cerebellum are ___________ while the smaller creases are called ________

A

Fissures; folia

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2
Q

Fissures divide the cerebellum into

A

Lobes and lobules

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3
Q

*The two hemispheres of the cerebellum are joined midline by the

A

Vermis

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4
Q

What are the main lobes of the cerebellum

A

Posterior, anterior, flocculonodular

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5
Q

What defines the flocculus and vermis (the nodule) to form the flocculonodular lobe

A

Posterolateral fissure

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6
Q

*The inferior cerebellar peduncle does what

A

Afferents to the cerebellum from the spinal cord and brainstem

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7
Q

*What is composed of recipricol fibers b/n the cerebellum and vestibular structures

A

Juxtarestiform body (wall of 4th ventricle)

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8
Q

*What part of the cerebellum has fibers arising in SC or medulla

A

Restiform body

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9
Q

*What is the largest cerebellar peduncle? What does it do?

A

Middle; emerges laterally from the basal pons and is composed of afferents to the cerebellum from the contralateral pontine nuclei

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10
Q

*What is unique about the superior cerebellar peduncle

A

It is most efferent fibers from the cerebellar nuclei and is distributed to the diencephalon and brainstem

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11
Q

What are the primary afferents of the cerebellum

A

Deep cerebellar nuclei

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12
Q

What are the main deep cerebellar nuclei

A
  • Dentate
  • Interposed comprised of emboliform (anterior interposed) and globose (posterior interposed)
  • Fastigial
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13
Q

*Each folium of the the cerebellum has a superficial layer ___________ and a core of myelinated fibers ___________

A

Cerebellar cortex; arbor vitae

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14
Q

What are the layers of the cerebellar cortex

A

-purkinje -granule cell -molecular

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15
Q

The granule cell layer is composed of

A

Cell-dense inner region immediately adjacent to white mayyer core

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16
Q

*What are the purkinje cells

A

Only efferent neurons of the cerbellum

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17
Q

What are the granule cells

A

Excitatory neurons that synapse w/ purkinje cells and the molecular layer (basket and stellate cells) They extend parallel fibers

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18
Q

What are the golgi cells

A

Inhibitory cells within the granular layer, extend dendrites into molecular

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19
Q

*What are the basket and stellate cells

A

Inhibitory cells in the molecular layer

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20
Q

What are mossy fibers

A

Cerebellar afferent axons that originate from cerebellar nuclei and other nuclei in the SC, medulla, pons

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21
Q

The mossy fibers branch in granular layer to form

A

Mossy fiber rosette

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22
Q

What gives the mossy fibers their appearance

A

Cerebellar glomerulus

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23
Q

What are excitatory to granule cell and golgi cell dendrite

A

Mossy fibers

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24
Q

What are the afferent fibers to the cerebellar cortex

A

Climbing fibers and multilayered fibers

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25
Q

Climbing fibers arise from

A

Inferior olivary nuclei

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26
Q

What do olivocerebellar fibers do

A

Send collaterals to the appropriate cerebellar nucleus that corresponds to the overlying cortical zone

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27
Q

What is the function of the climbing fibers

A

Exciting purkinje cells

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28
Q

Where are multilayered cells from

A

Locus ceruleus (noradrenergic) Raphe nuclei (serotinergic) Hypothalamus

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29
Q

The main function of the multilayered fibers are

A

Decreasing spontaneous discharge rates of purkinje cells

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30
Q

Which cerebellar fibers innervate all major cell types

A

Multilayered cells

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31
Q

*What are the functional subdivisions of the cerebellum

A

Pontocerebellum Vestibulocerebellum Spinocerebellum

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32
Q

*What is the pontocerebellum function

A

-comprises the majority of the cerebellar hemisphere and dentate nuclei -muscle coordination, speed/force/trajectory of movements

33
Q

What is the function of the vestibulocerebellum

A
  • Equated with flocculonodular lobe and fastigial nuclei
  • maintenance of balance/EQ
34
Q

What is the function of the spinocerebellum

A
  • approximates the vermins and surrounding area with the globose and emboliform nuclei
  • coordinates muscle tone/posture
35
Q

The vestibulocerebellum LMN output is

A

B/l bia vestibulospinal and reticulospinal projections

36
Q

What afferents does the spinocerebellum receive

A

-spinocerebellar and cuneocerebellar tracts -info from muscle, joint, and cutaneous receptors

37
Q

Fibers of the spinocerebellum terminate

A

In the cortex of the ipsilateral vermis and adjacent paravermis

38
Q

The output of the spinocerebellum is focused primarily on

A

Control of axial and limb musculature

39
Q

What is the pathway for axial movements from the spinocerebellum

A

Vermal cortex and fastigial efferents —> vestibular and reticular nuclei

40
Q

What is the limb pathway from the spinocerebellum

A

Globose and emboliform —> superior cerebellar peduncle —> red nucleus and thalamus

41
Q

What are the principal afferents of pontocerebellum

A

Pontocerebellar fibers -they cross to the opposite side of the brainstem -enter via middle cerebellar peduncle -terminate predominantly in the lateral part of the cerebellar hemisphere

42
Q

What is the primary output of hte pontocerebellum

A

Dentate nucleus -projects to the contralateral red nucleus and ventral lateral nucleus of the thalamus via the superior cerebellar peduncle -VLN (thalamus) projects to motor cortex

43
Q

Lesions of the lateral cerebellum

A

-Result in deterioration of coordinated movement (dyssynergia) -May also decrease muscle tone (hypotonia) and DTR -Ataxia involving extremities -May also have unsteady gait w/ tendency to lean toward side

44
Q

Dysmetria can result from

A

Cerebellar lesions -this is past pointing and is apparent in patients when they attempt to point to objects

45
Q

Tremors can result from

A

Lateral cerebellar lesions -can be kinetic (voluntary movements toward the end of the movement) or static (when they stand with upper extremities extended)

46
Q

The semicircular canals record

A

Angular accelerations

47
Q

The otolith organs record

A

Linear acceleration

48
Q

Receptors in the vestibular organs are innervated by primary afferent fibers of

A

Vestibular ganglion (scarpa ganglion)

49
Q

Central processes of the bipolar cells of the vestibules enter the brainstem and terminate

A

In the ipsilateral vestibular nuclei and cerebellum

50
Q

The superior vestibular nucleus

A

Is superolateral in the central pons bordered by the restiform body and 4th ventricle

51
Q

Where is the medial vestibular nucleus

A

Lateral floor of 4th ventricle throughout most of its rostrocaudal extent

52
Q

Where is the lateral vestibular nucleus

A

Lies lateral to the medial vestibular nucleus and contains large neurons (Deiters cells)

53
Q

Where is the inferior vestibular nucleus

A

Located lateral to the medial vestibular nucleus, extends through much of the medulla

54
Q

The primary vestibular afferents enter the brainstem where

A

Pontomedullary junction -they transverse the restiform body and bifurcate into ascending and descending branches

55
Q

Afferent fibers from the semicircular canals project where

A

Superior and medial vestibular nuclei

56
Q

The otolith organs project primarily to

A

Lateral, medial, and inferior vestibular nuclei

57
Q

Saccular afferents project to neurons in the

A

Contralateral oculomotor nucleus to influence vertical eye movements

58
Q

Vestibular nuclei show what type of selectivity

A

Directional to cause certain head movements

59
Q

Superior and medial vestibular nuclei receive information from

A

Otolith receptors and one semicircular canal pair (either horizontal or vertical)

60
Q

Lateral and inferior vestibular nuclei receive information from

A

Several canal pairs and otolith receptors

61
Q

What is the vestibuloocular reflex

A

Compensatory mechanism that allows you to track a fixed object while moving

62
Q

What is the pathway for the vestibuloocular reflex

A

Axons through medial longitudinal fasiculus —> contralateral abducens nucleus —> abducens motor neurons send excitatory impulses via CN6 —>ipsilateral lateral rectus m + contralateral occulomotor nucleus (medial rectus m)

63
Q

How is the vestibuloocular network modulated

A

-vestibular neurons send excitatory signals to ipsilateral oculomotor nucleus -vestibular neurons carry inhibitory signals to ipsilateral abducens nucleus

64
Q

What is the slow phase of nystagmus

A

Eyes move opposite direction of head rotation

65
Q

What is the fast phase of nystagmus

A

Eyes moving in the same direction as the head

66
Q

How is nystagmus named

A

Direction of head rotation

67
Q

Slow phase is dependent on what CN

A

3, 4, 6

68
Q

What is caloric nystagmus

A

Warm water in the ear causes looking towards that side Cold water in the ear causes opposite eye movements

69
Q

What is the oculoclonic reflex

A

Doll’s eyes movement Intact= both eyes looking in direction of fluid in ear

70
Q

The slow phase of the oculoclonic reflex is mediated by

A

Vestibular nuclei (CN 3, 4, 6)

71
Q

The fast phase of the oculoclonic reflex is mediated by

A

Signals that originate from the reticular formation

72
Q

Lesioned RF but intact brainstem does what with oculoclonic reflex

A

Deviation of eyes in the direction of the slow phase

73
Q

What is the name of the name of the brainstem circuitry that controls rapid eye movement

A

Saccades

74
Q

What contains premotor neurons that project to the extraocular motor nuclei

A

Pontine reticular formation/paramedian pontine reticular formation

75
Q

Lesions in the pontine reticular formation/paramedian pontine reticular formation cause

A

Horizontal gaze palsies -assuming the horizontal gaze center is involved

76
Q

What are the cells of the pontine reticular formation that project to the extraocular motor neurons

A

Excitatory burst neurons Inhibitory burst neurons

77
Q

When gaze shifts right what do the EBN and IBN do

A

EBN activate CN6 on the right IBN inhibit CN 6 on the left

78
Q

What carries information about the direction that the eyes should move

A

MLF (medial longitudinal fasiculus)

Neuro Exam 2 (21 decks)

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