Motor Control I,II and III Flashcards

1
Q

What are the 3 levels of motor control?

A

High
Middle
Low

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2
Q

What is the function of high motor control?

A

Strategy
The goal and the movement strategy

to best achieve this goal
Wanting to do something

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3
Q

What is the function of middle motor control?

A

Tactics

The sequence of spatiotemporal muscle contractions to achieve a goal smoothly and accurately

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4
Q

What is the function of low motor control?

A

Execution Activation of motor neuron and interneuron pools to generate goal-directed movement
Actually doing it

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5
Q

What structures are involved in high centre motor control?

A

Neocortex

Basal ganglion

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6
Q

What structures are involved in middle centre motor control?

A

Motor cortex

Cerebellum

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7
Q

What functions are involved in low centre motor control?

A

Brainstem

Spinal cord

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8
Q

What do lateral pathways control?

A

Voluntary movements of distal muscles

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9
Q

What do ventromedial pathways control?

A

Posture and locomotion

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10
Q

What are the ventromedial pathways?

A
  • Tectospinal tract
  • Vestibulospinal
  • Reticulospinal
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11
Q

What are the lateral pathways?

A

Lateral and anterior Corticospinal tract

Rubrospinal tract

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12
Q

Which is the largest descending pathway?

A

Lateral corticospinal

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13
Q

Where does 2/3 of the CST originate?

A

Area 4 and 6

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14
Q

What does the CST control?

A

VOLUNTARY motor control

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15
Q

Where does the CST decussate?

A

Medulla

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16
Q

Which side of the body does the right motor cortex control?

A

Left side of the body

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17
Q

Where do upper CST axons synapse with LMN?

A

Ventral horn

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18
Q

Where does the RBS originate?

A

Magnocellular red nucleus of midbrain

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19
Q

Where does RBS recieve its inputs from?

A

Same cortical areas as CST

Areas 4 and 6

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20
Q

If you lesion the CST what can happen?

A

The RBS can in time take over function

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21
Q

If you lesion both the CST and RBS what happens?

A

Lose restored functions

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22
Q

Can the RST assume almost all the duties of the CST when the CST is lesioned?

A

Yes

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23
Q

What is the function of the vestibulospinal tract?

A

Maintains posture by detecting movement of the head

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24
Q

What is the function of the tectospinal tract?

A

Give reflex movement based on visual stimuli

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25
Q

Does the TST decussate?

A

Yes

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26
Q

What does the TST co-ordinate?

A

Eye movements and reflexes

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27
Q

Do VST decussate?

A

No

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28
Q

Which ventromedial pathways control muscle tones and reflexes?

A

Pontine reticulospinal tract

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29
Q

Where do pontine and medullary reticulospinal tracts originate?

A

Reticular formation of pons and medulla

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30
Q

Which ares of the brain control precise voluntary movement?

A

Primary motor cortex

And pre-motor areas

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31
Q

How do UMN from cerebral cortex control LMN?

A

Cross over to control the LMN in lateral and medial ventral horns

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32
Q

What is the precentral gyrus?

A

Primary motor cortex

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33
Q

Where do a mosaic of premotor areas lie?

A

Rostrally to the primary motor cortex

34
Q

What is area 4?

A

Primary motor area

35
Q

What is area 6?

A

Pre-motor area

36
Q

What does the central sulcus separate?

A

Primary motor area

From primary sensory area

37
Q

What is meant by the somatotopic maps in humans?

A

Specific areas in the brain control very specific parts of the body
E.g a specific area on the pre-central gyrus in the brain will control all movements of the hands

38
Q

Does the body map into the brain in a proportionate way?

A

No

Completely disproportionate

39
Q

Why is the somatotopic map disproportionate?

A

Because some parts of the body although small can be highly sensitive and require very fine tuning

40
Q

What are the 2 somatotopic maps in area 6?

A

Premotor area

Supplementary motor area

41
Q

Is the somatotopic motor map precise?

A

No

42
Q

Does one cell in the motor cortex stimulate one certain muscle?

A

No

43
Q

What generates mental image of body in pace?

A

Somatosensory, proprioceptive and visual inputs from posterior parietal cortex

44
Q

Where are decisions made about what actions/movements to take and their likely outcome?

A

Motor areas

And their association areas

45
Q

If you only think about doing a movement but do not carry the movement out which part of the brain is active?

A

Area 6

46
Q

What are the 2 reticulospinal tracts?

A

Pontine

Medullar reticulopsinal tract

47
Q

Where does the RST decussate?

A

As the fibres emerge from the red nucleus

48
Q

What does the anterior CST control?

A

Voluntary movement ofp proximal muscles

49
Q

Does one cell in the motor cortex stimulate one certain muscle?

A

No

Stimulating a certain area will lead to an overall behavious

50
Q

When do neurons in the premotor area begin firing AP?

A

One second before a movement occurs

51
Q

What does babinski’s signs indicate?

A

UMN lesion

52
Q

Where does major subcortical input to area 6 come from?

A

Ventral lateral nucleus in dorsal thalamus

53
Q

Function of basal ganglia

A

Modulating, refining and terminating movements and decisions made by the cortex

54
Q

What composes the corpus striatum?

A

Caudate nucleus and putamen

55
Q

What are the input zones of the basal ganglia?

A

Caudate nucleus

Putamen

56
Q

What makes up the lentiform nucleus?

A

Putamen and globus pallidus

57
Q

Where does the corpus striatum receive input from?

A

All over the cortex

58
Q

What do neurons in the putamen and caudate nucleus receive from the motor cortex? direct pathway

A

Excitatory (glutamergic) cortical inputs on dendrites

59
Q

Where does major subcortical input to area 6 come from?

A

VLo from thalamus

60
Q

What are the components of the basal ganglia?

A

Caudate nucleus
Putamen
Globus pallidus
Substantia nigra

61
Q

Where is the substantia nigra located?

A

Midbrain

62
Q

Describe the cortex -> basal ganglia -> thalamus -> SMA pathway? Direct pathway

A
  1. Motor cortex sends an excitatory message to the striatum (putamen and caudate nucleus)
  2. Excitatory neuron synapses with an inhibitory neuron in the striatum
  3. This inhibitory neuron then heads for the globus pallidus
  4. Inhibitory neuron in the striatum is more excited than normal due to the excitation message from the cortex
  5. When the globus pallidus is inhibited its activity it turned down
  6. Meaning it can no longer inhibit the thalamus
  7. Thalamus is more active (VLo)
  8. Sends more excitatory messages to the SMA (supplementary motor area)
  9. So functional consequence of cortical activation of putamen is excitation
63
Q

Where does the motor cortex send excitatory signals to? direct pathway

A

Striatum

64
Q

What is the effect of excitatory signals to the striatum? direct pathway

A

Excitation of an inhibition pathway to the globus pallidus

65
Q

Where does the enhanced inhibitory pathway from the striatum go to? direct pathway

A

Globus pallidus

66
Q

What is the effect of the inhibitory signals to the globus pallidus? direct pathway

A

Inhibits it further

67
Q

At rest what does the globus pallidus do to the thalamus?

A

Inhibits it

68
Q

What does area 6 require for decision making?

A

Signals from the thalamus

69
Q

When the globus pallidus is inhibited what can now proceed? Direct pathway

A

The thalamus is uninhibited and can send VLo signals to area 6

70
Q

What is the functional consequence of cortical activation of putamen? direct pathway

A

Excitation

71
Q

When there is a lot of cortical input to the basal ganglia what happens?

A

The globus pallidus is inhibited and therefore the thalamus is disinhibited and so can excited neurones in SMA

72
Q

What is Parkinson’s disease caused by?

A

Degeneration of neurons in the substantia nigra and their domaninergic input to the stiratum

73
Q

Which neurotransmitter is affected in Parkinson’s disease?

A

Dopamine

74
Q

How does dopamine affect pathways?

A

can enhance cortical inputs through the “direct” pathway and suppress inputs through “indirect” pathway

75
Q

What happens in the depletion of dopamine?

A

Closes down the activation of the focussed motor activities that funnel through the thalamus to SMA

76
Q

What causes huntington’s disease?

A

caused by profound loss of caudate, putamen and globus pallidus

77
Q

What is there a loss of in Hungtington’s disease?

A

Inhibitory effects of the basal ganglia

78
Q

What % of neurons of the brain are located in the cerebellum?

A

50%

79
Q

What does the cerebellum introduce to the cortex?

A

Further refinement

80
Q

What do lesions to the cerebellum produce?

A

uncoordinated inaccurate movements : ataxia : fail to touch nose with eyes shut

81
Q

What does the cerebellum instruct?

A

Direction, timing and force

82
Q

What does VLo mean?

A

Ventrolateral thalamus