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Human Physiology 2 - Unit 2 - Zach H. > Lecture 12: Contributions of Cerebellum & Basal Nuclei to Motor Function I > Flashcards

Lecture 12: Contributions of Cerebellum & Basal Nuclei to Motor Function I Flashcards

1
Q

What does the primary motor cortex (area 4) signal?

A

Motor neurons to contract skeletal muscle fibers.

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2
Q

What tract does the primary motor cortex signal via?

A

Via the corticospinal (pyramidal tract) tract.

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3
Q

What are the executed commands of the primary motor cortex preceded by?

A

Extensive processing by cerebellum and basal nuclei.

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4
Q

What does the premotor cortex (area 6) plan?

A

Movements based on sensory and visual cues.

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5
Q

What does the supplementary motor area (area 6) function to do?

A

Retrieves and coordinates memorized motor sequences.

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6
Q

Which cortex retrieves and coordinates memorized motor sequences?

A

supplementary motor area (area 6)

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7
Q

Which cortex plans movements based on sensory and visual cues?

A

pre-motor cortex (area 6)

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8
Q

Which cortex signals motor neurons to contract skeletal muscle fibers?

A

primary motor cortex (area 4)

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9
Q

Which cortex provides most of the activating signals to the spinal cord?

A

motor cortex system

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10
Q

True or False:

Cord patterns are mainly determined by heredity and are “hard wired”.

A

True

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11
Q

What does the motor cortex system issue?

A

Sequential and parallel commands that initiate various cord patterns.

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12
Q

List basic functions of the cerebellum.

A
  • NOT essential for locomotion
  • helps sequence motor activities
  • monitors and makes corrective adjustments to motor activities while they are being executed
  • compares actual movements with intended movements
  • aids cortex in planning next sequential movement
  • learns by its mistakes
  • functions with spinal cord to enhance the stretch reflex
  • functions with brain stem to make postural movements
  • functions with cerebral cortex to provide accessory motor functions
  • turns on antagonist at appropriate time
  • helps program muscle contraction in advance
  • functions mainly when muscle movements have to be rapid
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13
Q

What does the cerebellum play a major role in?

A

Timing of motor activities and in rapid, smooth progression from one muscle movement to the next.

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14
Q

What does removal of the cerebellum cause?

A

Body movements to become highly abnormal.

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15
Q

True or False:

Electrical excitation of the cerebellum does not cause any conscious sensation and rarely causes any motor movement.

A

True

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16
Q

What 3 lobes is the cerebellum anatomically divided into?

A

> Anterior Lobe
Posterior Lobe
Flocculonodular Lobe (associated with vestibular system)

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17
Q

What are the two hemispheres of the cerebellum separated by?

A

vermis

each hemisphere is divided into an intermediate zone and a lateral zone

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18
Q

What zones are the two hemispheres of the cerebellum divided into?

A

intermediate zone and lateral zone

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19
Q

What lobe of the cerebellum is evolutionarily the oldest?

A

flocculonodular lobe

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20
Q

What and where is the vermis; with what functions is it associated?

A

> the vermis separates the hemispheres of the cerebellum

> vermis -> location for control functions for muscle movements of the axial body, neck, shoulders, and hips.

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21
Q

What does the intermediate zone control?

A

Concerned with controlling muscle contractions in the distal portions of the upper and lower limbs, especially hands, feet, fingers, and toes.

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22
Q

What is the lateral zone associated with?

A

Associated with cerebral cortex with planning of sequential motor movements.

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23
Q

Does the cerebellar cortex have 6 layers?

A

No - only 3

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24
Q

What are the characteristics of the cortex of the cerebellum?

A
  • like the cerebral cortex, this is gray matter and consists of multiple layers of cells, dendrites, and synapses.
  • consists of transversely arranged narrow gyri called folia
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25
Q

What do the intracerebellar nuclei of the cerebellum make up?

A 
Make up an inner layer of gray matter and include the following pairs of nuclei:
  > dentate
  > emboliform 
  > globose 
  > fastigial
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26
Q

What would lesions in the dentate nuclei, emboliform nuclei, and globose nuclei cause?

A

extremity ataxia

ataxia is abnormal movements of the limb, especially distal part of limb

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27
Q

What would a lesion in the fastigial nuclei cause?

A

trunk ataxia

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28
Q

Where do fibers from the dentate nuclei, emboliform nuclei, and globose nuclei project to?

A

red nucleus

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29
Q

Which intracerebellar nuclei are related to limb musculature and fine manipulative movements?

A
  • dentate nuclei
  • emboliform nuclei
  • globose nuclei
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30
Q

Where do fibers from the fastigial nuclei project to?

A
  • reticular formation

- vestibular nuclei

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31
Q

Which intracerebellar nuclei is related to postural activity and limb movements via reticulospinal and vestibulospinal tracts (balance and equilibrium)?

A
  • fastigial nuclei
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32
Q

Which cells make up the cerebellar cortex?

A

> granular cells
golgi cells
basket cells
stellate cells

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33
Q

Which two cell types of the cerebellar cortex provide lateral inhibition on adjacent Purkinje cells to provide damping?

A
  • basket cells

- stellate cells

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34
Q

What is the only cell type in the cerebellar cortex that is excitatory?

A

granular cells

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35
Q

What is the only cell type in the cerebellar cortex that is excitatory?

A

granular cells

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36
Q

What do axons from granular cells form?

A

Axons from parallel fibers in cortex (excitatory)

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37
Q

Where do golgi cells project from and to?

A

From parallel fibers to granular cell bodies (inhibitory)

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38
Q

Where do basket cells project from and to?

A

From parallel fibers to Purkinje axon hillock (inhibitory)

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39
Q

Where do stellate cells project from and to?

A

From parallel fibers to Purkinje dendrites (inhibitory)

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40
Q

What are the three layers of the cerebellar cortex?

A
  • Granular Layer
  • Purkinje Cell Layer
  • Molecular Layer
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41
Q

Which layer of the cerebellar cortex is the innermost layer?

A

Granular Layer

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42
Q

Which layer of the cerebellar cortex is the middle layer?

A

Purkinje Cell Layer

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43
Q

Which layer of the cerebellar cortex is the outermost layer?

A

Molecular Layer

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44
Q

What cell types make up the granular layer of the cerebellar cortex?

A

Made up of:
> granule cells
> Golgi type II cells
> glomeruli

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45
Q

Axons of what fibers synapse with granular cells and Golgi type II cells in the glomeruli?

A

mossy fibers

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46
Q

What cell types are found in the molecular layer of the cerebellar cortex?

A 
Contains:
  > stellate cells 
  > basket cells 
  > Purkinje dendrites
  > Golgi type II cells 
  > axons of granule cells (parallel fibers)
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47
Q

What cell type does the Purkinje layer of the cerebellar cortex contain?

A

Purkinje cells

48
Q

True or False:

Purkinje cells are ONLY output from the cortex.

A

True

49
Q

Is the Purkinje cells ouput always inhibitory.

A

True

50
Q

What are the characteristics of Purkinje cells?

A

> extensive dendritic branching

> receive input from parallel fibers (20,000 synapses between parallel fibers and one Purkinje cell).

> project to intracerebellar nuclei (inhibitory)

51
Q

To which nuclei do Purkinje cells project to?

A

intracerebellar nuclei (inhibitory)

52
Q

Which fibers in the cerebellar cortex are afferent fibers?

A
  • climbing fibers

- mossy fibers

53
Q

What are the characteristics of climbing fibers (afferent)?

A

> originate from medullary olives

> make multiple synapses with Purkinje cells

> provide high frequency bursts (complex spikes)

> “condition” the Purkinje cells

> play a role in motor learning

54
Q

What are the characteristics of mossy fibers?

A

> originate from multiple centers in brainstem and spinal cord, including:

  • vestibulocerebellar tracts
  • spinocerebellar tracts
  • pontocerebellar tracts

> make multiple syanpses on Purkinje cells and result in simple spikes

> synapse on granule cells in glomeruli

55
Q

Where do climbing fibers (afferent) originate from?

A

medullary olives

56
Q

Where do mossy fibers (afferent) originate from?

A

multiple centers in brainstem and spinal cord, including vestibulocerebellar, spinocerebellar, and pontocerebellar tracts

57
Q

Where do mossy fibers (afferent) of the cerebellar cortex synapse?

A

On granule cells in glomeruli.

58
Q

What cell makes up the efferent axons of the cerebellar cortex?

A

Purkinje cell axons

59
Q

What are the characteristics of Purkinje cell axons (efferent)?

A

> only output from cerebellar cortex

> output is always inhibitory

> GABA

> projects to deep cerebellar nuclei and vestibular nucleus

> modulates output of cerebellum and provides synergy (regulates rate, range, and direction of movement)

60
Q

Which efferent axon from the cerebellar cortex modulates output of cerebellum and provides synergy?

A

Purkinje cell axons

61
Q

Where do Purkinje cell axons project to?

A

To deep cerebellar nuclei and vestibular nucleus.

62
Q

Where do all climbing fibers originate from?

A

Inferior Olives

63
Q

True or False:
Mossy fibers send excitatory collaterals to deep nuclear cells and then synapse in granular layer with thousands of granule cells.

A

True

64
Q

How many functional units are there in the cerebellar cortex?

A

30 million

65
Q

Output from a functional unit is from what type of cell?

A

From a deep nuclear cell

66
Q

Fill in the Blank:

Each functional unit is centered on a _____ cell and a corresponding _____ _____ cell.

A

Purkinje; Deep Nuclear

67
Q

Afferent inputs to the cerebellum are mainly from what fibers?

A

> mossy fibers

> climbing fibers

68
Q

Do basket and stellate cells function as inhibitory cells in the cerebellar cortex?

A

Yes

69
Q

What type of cell does Purkinje cells inhibit?

A

Deep Nuclear Cells

70
Q

True or False:

Granule cells send axons to outer cerebellar surface; axons brach in two directions parallel to folia.

A

True

71
Q

Study Figure 57-7

A

“Neuronal circuit of the cerebellar cortex and Intracerebellar nuclei”

72
Q

What three levels does the nervous system use the cerebellum to coordinate motor control functions?

A
  • vestibulocerebellum
  • spinocerebellum
  • cerebrocerebellum
73
Q

What part of the cerebellum does the vestibulocerebellum consist of?

A

> flocculonodular lobe

> vermis

74
Q

What does the vestibulocerebellum control?

A

balance and eye movements

75
Q

What two systems does the vestibulocerebellum receive fibers from?

A

> vestibular system

> oculomotor system (pontocerebellar fibers)

76
Q

Where does the vestibulocerebellum primarily send output to?

A

vestibular system

77
Q

What happens if you have loss of flocculonodular lobes?

A

extreme disturbance of equilibrium and postural movements

78
Q

True or False:

The vestibulocerebellum evolved at about the same time as the vestibular system.

A

True

79
Q

What changes can occur when the cerebellum is removed?

A

> movements are slow to develop
force developed is weak
movements are slow to turn off

80
Q

What is the relationship of vestibulocerebellum to pendular movements?

A
  • most body movements are pendular (swing back and forth)
  • all pendular movements have tendency to overshoot
  • appropriate learned subconscious signals from intact cerebellum can stop movement precisely at intended point (= damping system)
81
Q

What parts of the cerebellum does the spinocerebellum mostly consist of?

A
  • vermis

- intermediate zone

82
Q

What is the function of the spinocerebellum?

A

Synergy: control of rate, force, range, and direction of movement.

83
Q

What kind of information does the spinocerebellum receive?

A
  • information from motor cortex and red nucleus telling cerebellum intended sequential plan of movement for the next few fractions of a second.
  • feedback information from periphery telling cerebellum what actual movements result.
84
Q

Where does the spinocerebellum send corrections to that it has compared from the two sources that it receives information from?

A
  • motor cortex via thalamus

- magnocellular potion of red nucleus

85
Q

What part of the cerebellum does the cerebrocerebellum consist of?

A

lateral parts of hemispheres

86
Q

What areas of the cerebral cortex are the cerebrocerebellum associated with?

A
  • premotor cortex
  • primary motor cortex
  • association somatosensory areas
87
Q

What projections do the cerebrocerebellum receive?

A

corticopontcerebellar

88
Q

What is the cerebrocerebellum involved in coordinating?

A

skilled movement and speech

89
Q

True or False:

The cerebrocerebellum plans as much as tenths of a second in advance of actual movements.

A

True

**referred to as “motor imagery”

90
Q

What is the definition of dysmetria?

A

Refers to a lack of coordination of movement typified by the undershoot or overshoot of intended position with hand, arm, leg, or eye.
It is a type of ataxia.
An inability to judge distance or scale.

91
Q

What is the definition of ataxia?

A

The loss of full control of bodily movements.

92
Q

What is the definition of past pointing?

A

In cerebellar disease, a patient attempting to reach a point with finger will overshoot it.

93
Q

What is the definition of dysdiadochokinesia?

A

Is a feature of cerebellar ataxia and may be the result of lesions to either the cerebellar hemispheres or the frontal lob, it can also be a combination of both.

94
Q

What is the definition of dysarthria?

A

Difficult or unclear articulation of speech that is otherwise linguistically normal.

95
Q

What is the definition of cerebellar nystagmus?

A

Disease affecting the vestibular organ in the inner ear causes an imbalance that leads to a mixed horizontal - torsional nystagmus usually associated with vertigo. Disease affecting the central connections of the vestibular system, including the cerebellum, may cause several forms of nystagmus.

96
Q

What is the definition of hypotonia?

A

Also known as floppy baby syndrome, is a state of low muscle tone (the amount of tension or resistance to stretch in a muscle) often involving reduced muscle strength.

97
Q

What afferent tracts go to the cerebellum?

A
  • Corticopontocerebellar
  • Vestibulocerebellar
  • Reticulocerebellar
  • Spinocerebellar
    > ventral
    > dorsal
  • Olivocerebellar
98
Q

What are the efferent tracts from the cerebellum?

A
  • cerebelloreticular
  • cerebellothalamocortical
  • cerebellorubral
  • cerebellovestibular
99
Q

What is the route of the corticopontocerebellar to the cerebellum?

A

motor and premotor cortices/Somatosensory cortex -> pontine nuclei -> lateral divisions of cerebellum

100
Q

Where does the vestibulocerebellar terminate in the cerebellum?

A

terminates in flocculonodular lobes

101
Q

Where does the reticulocerebellar tract primarily terminate in the cerebellum?

A

Terminates primarily in vermis.

102
Q

What afferent tracts to the cerebellum form the mossy fibers that terminate on the granule cells in the cerebellar cortex (excitatory)?

A
  • corticopontocerebellar
  • vestibulocerebellar
  • reticulocerebellar
  • spinocerebellar
103
Q

Where do dorsal spinocerebellar tracts come from and terminate in the cerebellum?

A

Muscle Spindles -> ipsilaterally in vermis and intermediate zones.

104
Q

What does the dorsal spinocerebellar apprise the cerebellum of momentary status of?

A
  • muscle contractions
  • degree of tension on the muscle spindles
  • positions and rates of movement of parts of the body
  • forces acting on surfaces of the body
105
Q

True of False:

The ventral spinocerebellar tract terminates both ipsilaterally and contralaterally.

A

True

106
Q

The ventral spinocerebellar tract is excited by signals coming from?

A
  • cortex via corticospinal and rubrospinal tracts

- internal motor pattern generators within spinal cord

107
Q

What does the ventral spinocerebellar tracts tell the cerebellum?

A
  • Which motor signals have arrived at the anterior horns.

- This feedback = efference copy of the anterior horn motor drive.

108
Q

What do axons of the olivocerebellar form?

A

climbing fibers

109
Q

Where do tracts from cerebelloreticular come from and to?

A

Fastigial nuclei -> reticular nuclei in pons and medulla

110
Q

Where do tracts from cerebellothalamocortical come from and to?

A

dentate, emboliform, globose nuclei -> thalamus -> motor cortex

111
Q

Where do tracts from cerebellorubral come from and to?

A

dentate, emboliform, globose nuclei -> red nucleus

112
Q

Where do tracts from cerebellovestibular come from and to?

A

cerebellum -> vestibular nuclei

113
Q

What do climbing fibers from the olivocerebellar (afferent) tracts cause?

A

Climbing fiber causes a single, prolonged (up to one second) action potential on each Purkinje cell with which it connects (one climbing fiber per 5-10 Purkinje cells).

114
Q

What is a complex spike?

A

Each signal (from climbing fiber) starts out as a strong spike and is followed by a series of weak secondary spikes.

115
Q

What do mossy fibers send excitatory signals to?

A

granule cells

116
Q

True or False:
In the olivocerebellar afferent tracts to the cerebellum, neurons project from inferior olivary nuclei (in medulla) to Purkinje cell dendrites (+) and to intracerebellar nuclei.

A

True

Human Physiology 2 - Unit 2 - Zach H. (11 decks)

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