12. contributions of cerebellum and basal nuclei to motor function

Question 1

What are functions of primary motor cortex (area 4)?

Answer 1

1. signal motor neuron to contract skeletal muscle fibers
2. uses corticospinal tract for signaling
3. commands have extensive processing from cerebellum and basal nuclei

Question 2

What are the functions of premotor cortex (area 6)?

Answer 2

1. plans movements based on sensory and visual cues

Question 3

What is the function of the supplementary motor area (area 6)?

Answer 3

1. retrieves and coordinates memorized motor sequences

Question 4

What are the functions of the motor cortex system?

Answer 4

1. provide activating signal to spinal cord
2. issues sequential and parallel commands that initiate carious cord patterns
3. cortical patterns are complex and can be learned
4. cord patterns are hereditary and hard wired

Question 5

What are key functions of the cerebellum?

Answer 5

1. timing of motor activities in rapid, smooth progression from one muscle movement to the next
2. helps sequence motor activities
3. monitors and makes corrective adjustments to motor activities during execution

Question 6

What does the vermis separate?

Answer 6

1. divides into intermediate zone and a lateral zone

Question 7

The cerebellum is divided into three different lobes anatomically. What are they?

Answer 7

1. anterior lobe
2. posterior lobe
3. flocculonodular lobe (associated with vestibular system)

Question 8

What is the vermis?

Answer 8

1. separates the intermediate zone and lateral zones

2. located for control functions for muscle movement of axial body, neck, shoulders, and hips

Question 9

What is the intermediate zone?

Answer 9

1. controls muscle contractions in distal portions of upper and lower limbs

Question 10

What is the lateral zone?

Answer 10

1. associates with cerebral cortex and plans sequential motor movements

Question 11

What forms the inner layer of gray matter, and what nuclei are contained within that region?

Answer 11

1. intracerebellar nuclei

2. dentate, emboliform, globose, fastigial nuclei pairs

Question 12

Where would a lesion have to occur to cause extremity ataxia?

Answer 12

1. dentate, emboliform, and globose nuclei
2. these fibers project into red nucleus
3. associate with limb musculature and fine manipulative movements

Question 13

What would cause trunk ataxia?

Answer 13

1. lesion to fastigial nucleus

Question 14

What are characteristics of fastigial nuclei?

Answer 14

1. fibers project into reticular formation and vestibular nuclei
2. related to postural activity and limb movements via reticulospinal and vestibulospinal tract

Question 15

What is the granular layer of the cerebellar cortex?

Answer 15

1. innermost layer of granule cells, golgi type II cells, and glomeruli
2. site where mossy fibers synapse with granular cells and golgi type II cells

Question 16

What is the purkinje cell layer of the cerebellar cortex?

Answer 16

1. middle layer of purkinje cells

Question 17

What is the molecular layer of the cerebellar cortex?

Answer 17

1. outermost layer.

2. stellate cells, basket cell, purkinje dendrite, golgi II, axons of granule cells

Question 18

What are granular cells?

Answer 18

excitatory cells that form parallel fibers in cortex

Question 19

What are golgi cells?

Answer 19

inhibitory cells that project from parallel fibers to granular cell bodies

Question 20

What are basket cells?

Answer 20

inhibitory cells that project from parallel fibers to purkinje axon hillock

Question 21

What are stellate cells?

Answer 21

inhibitory cells that project from parallel fibers to purkinje dendrites

Question 22

Which cells in the cerebellar cortex provide lateral inhibition on adjacent purkinje cells to provide damping?

Answer 22

basket and stellate cells

Question 23

What are some characteristics of purkinje cells?

Answer 23

1. only output from cortex and is always inhibitory
2. extensive dendritic branching
3. project to intracerebellar (inhibitory) nuclei

Question 24

What are cerebellar cortex climbing fibers?

Answer 24

1. orginate in medullary olives
2. condition purkinje cells and provide motor learning
3. multiple synapse with purkinje cells

Question 25

What are cerebellar cortex mossy fibers?

Answer 25

1. originate from vestibulocerebellar, spinocerebellar, and pontocerebellar tracts 2. multiple synapse on purkinje cells 3. synapse on granule cells in glomeruli

Question 26

What are the functions of the purkinje cell axons?

Answer 26

1. efferent fibers that regulate rate, range, directoin or movement 2. output is cerebellar cortex 3. GABA neurotransmitter

Question 27

What happens when mossy fibers enter the cerebellum from numerous sources?

Answer 27

1. excitatory collaterals are sent to deep nuclear cells and synapse in granular layer with thousand of granule cells 2. all originate from inferior olives

Question 28

What are the regions of the cerebellum that contribute to motor control?

Answer 28

1. vestibulocerebellum 2. spinocerebellum 3. cerebrocerebellum

Question 29

What are characteristics of teh vestibulocerebellum?

Answer 29

1. flocculonodular lobes and vermis | 2. control balance and eye movement

Question 30

What fibers are received by the vestibulocerebellum?

Answer 30

1. vestibular system | 2. oculomotor (pontocerebellar fibers)

Question 31

What happens if the vestibulocerebellum is damaged or the flocculonodular lobes are damaged?

Answer 31

1. equilibrium and postural movements disturbed

Question 32

What action is the vestibulocerebellum most known for?

Answer 32

1. relationship with pendular movements that continue to be "overshot" due to momentum

Question 33

What makes up the spinocerebellum?

Answer 33

1. vermis | 2. intermediate zone

Question 34

What are the functions of the spinocerebellum?

Answer 34

1. control rate, force, range and direction of movement

Question 35

What fibers/information does the spinocerebellum receive?

Answer 35

1. motor cortex and red nucleus information | 2. feedback from periphery to interpret actual movement

Question 36

Where are corrective signals sent after comparison at the spinocerebellum?

Answer 36

1. motor cortex via thalamus | 2. magnocellular portion of red nucleus

Question 37

What makes up the cerebrocerebellum?

Answer 37

lateral portion of hemispheres, that are associated with premotor, primary, and association somatosensory areas of cerebral cortex

Question 38

What information does the cerebrocerebellum receive?

Answer 38

1. corticolpontocerebellar projections

Question 39

What type of movements are the cerebrocerebellum most involved with?

Answer 39

1. skilled movement | 2. speech

Question 40

Where is motor imagery formed?

Answer 40

cerebrocerebellum

Question 41

Dysmetria?

Answer 41

inability to properly direct movements

Question 42

Ataxia?

Answer 42

loss of body movement

Question 43

Past-pointing?

Answer 43

evaluates the vestibular nerves. Generally will overshoot a point while attempting to touch it

Question 44

Dysdiadochokinesia?

Answer 44

cerebellar dysfunction with impaired ability to make movements with rapid motion changes

Question 45

Dysarthria?

Answer 45

poor speech articulation

Question 46

Cerebellar nystagmus?

Answer 46

eyeball tremor, when looking to one side of the head. Cerebellum damping fails or there is a flocculonodular lesion

Question 47

Hypotonia?

Answer 47

decreased muscle tone which indicates cerebellar facilitation loss.

Question 48

What are the afferent tracts to the cerebellum?

Answer 48

1. corticopontocerebellar 2. vestibulocerebellar 3. reticulocerebellar 4. spinocerebellar * all form mossy fibers that terminate on granule cells in cerebellar cortex.

Question 49

What is the function of the dorsal spinocerebellar tract to the cerebellum?

Answer 49

provides momentary status of: 1. muscle contractions 2. tension on muscle spindle 3. proprioception 4. body surface forces

Question 50

What are the functions of the ventral spinocerebellar tract?

Answer 50

1. feedback for what signals have reached the anterior spinal horns 2. excited by rubrospinal and corticospinal tracts

Question 51

Which axons form climbing fibers?

Answer 51

olivocerebellar tract to cerebellum.

Question 52

What are the efferent tracts from the cerebellum?

Answer 52

1. cerebelloreticular 2. cerebellothalamocortical 3. cerebellorubral 4. cerebellovestibular

Question 53

Where do the axons for cerebelloreticular tract run?

Answer 53

from fastigial nuclei to reticular nuceli in pons/medulla

Question 54

Where do axons from cerebellothalamocortical tract run?

Answer 54

from dentate, emboliform, globose nuclei to thalamus to motor cortex

Question 55

Where do axons from the cerebellorubral tract run?

Answer 55

dentate, emboliform, globose nuclei to red nucleus

Question 56

Where do axons from the cerebellovestibular tract run?

Answer 56

cerebellum to the vestibular nuclei.