Cerebellum and Movement

Question 1

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

Answer 1

10%

50%

Question 2

How does the cerebellum coordinate movement and postural control?

Answer 2

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

Question 3

What 3 things is the cerebellum involved in?

Answer 3

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

Question 4

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

Answer 4

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

Question 5

What does the cerebellar cortex do?

Answer 5

process information

Question 6

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

Answer 6

3

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

Question 7

What is deep to the cortex?

Answer 7

White matter, which consists of the cerebellar nuclei

Question 8

What cells are the output cells from the cerebellar cortex?

Answer 8

Purkinje cells

Question 9

Purkinje cells projections ____ the cerebellar nuclei and the vestibular nuclei

Answer 9

inhibit

Question 10

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

Answer 10

• Mossy fibers

- Climbing fibers

Question 11

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

Answer 11

• somatosensory
• arousal
• equilibrium
• cerebral cortex motor information

Question 12

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

Answer 12

• movement errors

Question 13

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

Answer 13

Purkinje

interneurons

Question 14

What are the 3 lobes of the cerebellum?

Answer 14

• anterior
• posterior
• flocculonodular

Question 15

Where is the flocculonodular lobe located?

Answer 15

tucked underneath the posterior lobe, touching the brainstem

Question 16

What are the 3 cerebellar peduncles?

Answer 16

• Superior cerebellar peduncles
• Middle cerebellar peduncles
• Inferior cerebellar peduncles

Question 17

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

Answer 17

superior

Question 18

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

Answer 18

middle

Question 19

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.

Answer 19

inferior

Question 20

List the 4 cerebellar nuclei from medial to lateral

Answer 20

• Fastigial nucleus
• Globose
• Emboliform
• Dentate

Question 21

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

Answer 21

• Midline vermis
• Paravermal hemisphere
• Lateral hemisphere

Question 22

What are the 3 broad classes of human movement?

Answer 22

• Equilibrium
• Gross movements of the limbs
• Fine, distal, voluntary movements

Question 23

The ____cerebellum regulates equilibrium.

Answer 23

vestibulocerebellum

Question 24

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

Answer 24

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

Question 25

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

Answer 25

visual, to influence eye movements and postural muscles

Question 26

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

Answer 26

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

Question 27

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

Answer 27

Ongoing movement via brainstem descending tracts

Question 28

Input to the cerebrocerebellum is received from where?

Answer 28

cerebral cortex fibers that synapse with neurons in the pons

Question 29

The ____cerebellum coordinates gross limb movements.

Answer 29

spinocerebellum

Question 30

The ____cerebellum coordinates distal limb voluntary movement.

Answer 30

cerebrocerebellum

Question 31

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

Answer 31

same

Question 32

Cerebellar signs are ____, why?

Answer 32

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.

Question 33

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

Answer 33

ataxia

Question 34

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

Answer 34

truncal ataxia

Question 35

Paravermal lobe cerebellar lesions result in what type of ataxia?

Answer 35

gait and limb ataxia

Question 36

Lateral cerebellar lesions result in what type of ataxia?

Answer 36

hand ataxia

Question 37

What do lesions involving the vestibulocerebellum cause?

Answer 37

- nystagmus - disequilibrium - difficulty maintaining sitting and standing balance (truncal ataxia)

Question 38

What do paravermal and cerebrocerebellar lesions result in?

Answer 38

dysarthria, which is slurred, poorly articulated speech

Question 39

Dysfunction of the spinocerebellum results in what?

Answer 39

ataxic gait

Question 40

Describe ataxic gait

Answer 40

wide-based, unsteady, staggering, and veering gait

Question 41

What cerebellar lobe is damaged in chronic alcoholism?

Answer 41

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

Question 42

Spinocerebellar lesions result in what type of ataxia?

Answer 42

limb ataxia

Question 43

Limb ataxia manifests itself in what ways?

Answer 43

- dysdiadochokinesia: inability to rapidly alternate movements - dysmetria: inability to accurately move an intended distance - action tremor

Question 44

How are action tremors compensated for?

Answer 44

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

Question 45

What do cerebrocerebellar lesions interfere with?

Answer 45

the coordination of fine finger movements

Question 46

Is all ataxia is caused by cerebellar lesions?

Answer 46

no

Question 47

What may also produce ataxia?

Answer 47

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

Question 48

Sensory deficits or paravermal cerebellar lesions may cause ataxia where?

Answer 48

in the lower limbs

Question 49

What test differentiates between sensory and cerebellar limb ataxia?

Answer 49

Rhomberg test

Question 50

What does the Rhomberg test measure?

Answer 50

The ability to use proprioceptive information for standing balance

Question 51

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

Answer 51

- 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.

Question 52

What is also impaired in sensory ataxia?

Answer 52

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

Question 53

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

Answer 53

No, all are normal

Question 54

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

Answer 54

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

Question 55

What are the 3 types of movements?

Answer 55

- Postural - Ambulatory - Reaching/grasping

Question 56

Posture is controlled by which brain region?

Answer 56

brainstem region

Question 57

Ambulation is controlled by which brain regions?

Answer 57

brainstem and spinal regions

Question 58

Reaching/Grasping is controlled by which brain region?

Answer 58

cerebral cortex

Question 59

What does postural control provide?

Answer 59

Orientation and balance

Question 60

What is orientation?

Answer 60

the adjustment of the body and head to vertical

Question 61

What is balance?

Answer 61

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

Question 62

How is postural control achieved?

Answer 62

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

Question 63

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

Answer 63

- Somatosensation - Vision - Vestibular

Question 64

What does somatosensation provide information about?

Answer 64

weight bearing and the relative positions of body parts

Question 65

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

Answer 65

provides information about movement and cues for judging upright

Question 66

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

Answer 66

head position relative to gravity and about head movement

Question 67

What 2 senses can predict destabilization?

Answer 67

visual and somatosensory

Question 68

Which senses are used to shape the motor reaction to instability

Answer 68

all 3: Somatosensation, Vision, and Vestibular

Question 69

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

Answer 69

Posturography

Question 70

__ sensory conditions can be tested in posturography.

Answer 70

Six

Question 71

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

Answer 71

- 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.

Question 72

During ambulation what does the swing limb do first?

Answer 72

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

Question 73

What 2 senses are essential for reaching and grasping?

Answer 73

- vision | - somatosensation

Question 74

What is the significance of vision for reaching/grasping?

Answer 74

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

Question 75

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

Answer 75

Feed-forward, or the preparation for movement

Question 76

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

Answer 76

from the visual cortex to the posterior parietal cortex

Question 77

What is grasping coordinated with?

Answer 77

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

Question 78

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

Answer 78

forward

Question 79

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

Answer 79

somatosensory information

Question 80

What does an evaluation of the motor system assess?

Answer 80

- strength - muscle bulk - muscle tone - reflexes - movement efficiency and speed - postural control - abnormal movements

Question 81

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

Answer 81

- Nerve - Neuromuscular junction - Muscle

Question 82

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

Answer 82

denervated muscle and myopathy

Question 83

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

Answer 83

using an oscilloscope and loudspeaker