Cerebellum and Movement Flashcards

1
Q

The cerebellum accounts for __% of the brain and __% of all of the neurons in the CNS

A

10%

50%

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2
Q

How does the cerebellum coordinate movement and postural control?

A

By comparing actual motor output with the intended movement and then adjusting the movement as necessary

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3
Q

What 3 things is the cerebellum involved in?

A
  • learning timing and rhythm of movements
  • synchronization of movements
  • learning to correct motor errors
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4
Q

Does damage to the cerebellum interfere with sensory perception or muscle strength?

A

No, however coordination of movement and postural control are degraded.

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5
Q

What does the cerebellar cortex do?

A

process information

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6
Q

How many layers are there to the cerebellar cortex? What is contained within each layer

A

3

  • outer layer: interneurons
  • middle layer: Purkinje cell bodies
  • inner layer: interneurons
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7
Q

What is deep to the cortex?

A

White matter, which consists of the cerebellar nuclei

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8
Q

What cells are the output cells from the cerebellar cortex?

A

Purkinje cells

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9
Q

Purkinje cells projections ____ the cerebellar nuclei and the vestibular nuclei

A

inhibit

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10
Q

What are the 2 types of afferents that enter the cerebellar cortex?

A
  • Mossy fibers

- Climbing fibers

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11
Q

What type of information to the mossy fibers convey to the cerebellum?

A
  • somatosensory
  • arousal
  • equilibrium
  • cerebral cortex motor information
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12
Q

What type of information to the climbing fibers convey to the cerebellum?

A
  • movement errors
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13
Q

Climbing fibers synapse with _____ cells, whereas mossy fibers synapse with _______ that convey information to the Purkinje cells

A

Purkinje

interneurons

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14
Q

What are the 3 lobes of the cerebellum?

A
  • anterior
  • posterior
  • flocculonodular
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15
Q

Where is the flocculonodular lobe located?

A

tucked underneath the posterior lobe, touching the brainstem

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16
Q

What are the 3 cerebellar peduncles?

A
  • Superior cerebellar peduncles
  • Middle cerebellar peduncles
  • Inferior cerebellar peduncles
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17
Q

The _____ cerebellar peduncle connects to the midbrain and contains most of the cerebellar efferent fibers

A

superior

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18
Q

Fibers from the cerebral cortex synapse in the pons, and the information then travels via axons in the ____ peduncle into the cerebellum

A

middle

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19
Q

The _____ peduncle brings afferent information from the brainstem and spinal cord into the cerebellum and sends efferent from the cerebellum to the vestibular nuclei and reticular nuclei in the brainstem.

A

inferior

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20
Q

List the 4 cerebellar nuclei from medial to lateral

A
  • Fastigial nucleus
  • Globose
  • Emboliform
  • Dentate
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21
Q

Vertically, the cerebellum can be divided into sections, what are they?

A
  • Midline vermis
  • Paravermal hemisphere
  • Lateral hemisphere
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22
Q

What are the 3 broad classes of human movement?

A
  • Equilibrium
  • Gross movements of the limbs
  • Fine, distal, voluntary movements
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23
Q

The ____cerebellum regulates equilibrium.

A

vestibulocerebellum

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24
Q

The vestibulocerebellum is the functional name from the _____ lobe why?

A

flocculonodular, because is receives information directly from vestibular receptors and connects reciprocally with the vestibular nuceli

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25
Q

The vestibulocerebellum also receives information from ____ areas of the brain to influence what?

A

visual, to influence eye movements and postural muscles

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26
Q

The spinocerebellum is the functional name of the ____ and the ____ region, why?

A

vermis and paravermal region, because of its extensive connections with the spinal cord

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27
Q

Information that converges in the spinocerebellum is used to control what?

A

Ongoing movement via brainstem descending tracts

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28
Q

Input to the cerebrocerebellum is received from where?

A

cerebral cortex fibers that synapse with neurons in the pons

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29
Q

The ____cerebellum coordinates gross limb movements.

A

spinocerebellum

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30
Q

The ____cerebellum coordinates distal limb voluntary movement.

A

cerebrocerebellum

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31
Q

Unilateral lesions of the cerebellum affect the ____ side of the body.

A

same

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32
Q

Cerebellar signs are ____, why?

A

ipsilateral, because the output paths of the medial descending tracts remain ipsilateral and because cerebellar efferents project to the contralateral cerebral cortex and red nucleus whose descending tracts cross the midline.

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33
Q

What type of movement disorder is common to all lesions of the cerebellum?

A

ataxia

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34
Q

Vermal and flocculonodular lobe cerebellar lesions result in what type of ataxia?

A

truncal ataxia

35
Q

Paravermal lobe cerebellar lesions result in what type of ataxia?

A

gait and limb ataxia

36
Q

Lateral cerebellar lesions result in what type of ataxia?

A

hand ataxia

37
Q

What do lesions involving the vestibulocerebellum cause?

A
  • nystagmus
  • disequilibrium
  • difficulty maintaining sitting and standing balance (truncal ataxia)
38
Q

What do paravermal and cerebrocerebellar lesions result in?

A

dysarthria, which is slurred, poorly articulated speech

39
Q

Dysfunction of the spinocerebellum results in what?

A

ataxic gait

40
Q

Describe ataxic gait

A

wide-based, unsteady, staggering, and veering gait

41
Q

What cerebellar lobe is damaged in chronic alcoholism?

A

anterior lobe section of the spinocerebellum due to malnutrition, resulting in the characteristic ataxic gait

42
Q

Spinocerebellar lesions result in what type of ataxia?

A

limb ataxia

43
Q

Limb ataxia manifests itself in what ways?

A
  • dysdiadochokinesia: inability to rapidly alternate movements
  • dysmetria: inability to accurately move an intended distance
  • action tremor
44
Q

How are action tremors compensated for?

A

By using movement decomposition, which consists of maintaining a fixed position of one joint while another joint is moving

45
Q

What do cerebrocerebellar lesions interfere with?

A

the coordination of fine finger movements

46
Q

Is all ataxia is caused by cerebellar lesions?

A

no

47
Q

What may also produce ataxia?

A

Interference with transmission of somatosensory information to the cerebellum, either by lesions of the spinocerebellar tracts or by peripheral neuropathy

48
Q

Sensory deficits or paravermal cerebellar lesions may cause ataxia where?

A

in the lower limbs

49
Q

What test differentiates between sensory and cerebellar limb ataxia?

A

Rhomberg test

50
Q

What does the Rhomberg test measure?

A

The ability to use proprioceptive information for standing balance

51
Q

How do Rhomberg test results differentiate between individuals with cerebellar limb ataxia and sensory ataxia?

A
  • Individuals with cerebellar limb ataxia are unable to stand with feet together, with or without vision, and have normal vibratory sense, proprioception, and ankle reflexes.
  • Individuals with sensory ataxia are able to stand steadily with feet together with eyes open for 30 seconds, but balance is impaired when the eyes are closed.
52
Q

What is also impaired in sensory ataxia?

A

Conscious proprioception and vibratory sense are impaired, ankle reflexes are decreased or absent.

53
Q

Are muscle strength, bulk, tone, and involuntary muscle contraction impaired in cerebellar lesions?

A

No, all are normal

54
Q

In summary, the cerebellum and basal ganglia are called the ____ circuits and adjust what?

A

control circuits that adjust the level of activity in the descending tracts

55
Q

What are the 3 types of movements?

A
  • Postural
  • Ambulatory
  • Reaching/grasping
56
Q

Posture is controlled by which brain region?

A

brainstem region

57
Q

Ambulation is controlled by which brain regions?

A

brainstem and spinal regions

58
Q

Reaching/Grasping is controlled by which brain region?

A

cerebral cortex

59
Q

What does postural control provide?

A

Orientation and balance

60
Q

What is orientation?

A

the adjustment of the body and head to vertical

61
Q

What is balance?

A

the ability to maintain the center of mass relative to the base of support

62
Q

How is postural control achieved?

A

By central commands to the lower motor neurons; the central output is adjusted to the environmental context by sensory input

63
Q

What 3 senses are used in order to orient to the world?

A
  • Somatosensation
  • Vision
  • Vestibular
64
Q

What does somatosensation provide information about?

A

weight bearing and the relative positions of body parts

65
Q

What does vision provide information about and what does it cue for?

A

provides information about movement and cues for judging upright

66
Q

What does vestibular input from receptors in the inner ear inform us about?

A

head position relative to gravity and about head movement

67
Q

What 2 senses can predict destabilization?

A

visual and somatosensory

68
Q

Which senses are used to shape the motor reaction to instability

A

all 3: Somatosensation, Vision, and Vestibular

69
Q

What device can be used to determine sensory organization and muscle coordination?

A

Posturography

70
Q

__ sensory conditions can be tested in posturography.

A

Six

71
Q

Describe how the cerebral cortex, basal ganglia, cerebellum, and sensory information are used in normal human ambulation.

A
  • Cerebral cortex provides goal orientation and control of ankle movements.
  • Basal ganglia govern generation of force.
  • Cerebellum provides timing, coordination, and error correction.
  • Sensory information is used to adapt motor output appropriately.
72
Q

During ambulation what does the swing limb do first?

A

First it pushes downward and then backward against the support surface, in order to get the COG moving

73
Q

What 2 senses are essential for reaching and grasping?

A
  • vision

- somatosensation

74
Q

What is the significance of vision for reaching/grasping?

A

It provides information for locating an object in space and assessing its shape and size.

75
Q

What is the primary role of vision during reaching and grasping?

A

Feed-forward, or the preparation for movement

76
Q

The stream of visual information used for movement (“action stream”) flows from where to where?

A

from the visual cortex to the posterior parietal cortex

77
Q

What is grasping coordinated with?

A

Activity of the eyes, head, proximal upper limb, and trunk

78
Q

When the object one reaches for is contacted, grip force adjusts quickly, indicating feed-____ control.

A

forward

79
Q

After an object is grasped, what corrects any error in grip force?

A

somatosensory information

80
Q

What does an evaluation of the motor system assess?

A
  • strength
  • muscle bulk
  • muscle tone
  • reflexes
  • movement efficiency and speed
  • postural control
  • abnormal movements
81
Q

The purpose of nerve conduction studies in motor disorders is to differentiate among three possible sites of dysfunction, what are these 3 sites?

A
  • Nerve
  • Neuromuscular junction
  • Muscle
82
Q

Diagnostic EMG (using a needle electrode inserted into the muscle) is commonly used to distinguish between what 2 things?

A

denervated muscle and myopathy

83
Q

How is electrical activity of a msucle recorded in a diagnostic EMG?

A

using an oscilloscope and loudspeaker