Motor and premotor Cortex Flashcards

1
Q

what can the motor cortex be divided into?

A

primary motor cortex (M1)
Premotor cortex
supplementary area

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2
Q

True or false: there is more surface area of the motor cortex specific for fine motor movements

A

True, it is soma topically organized

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3
Q

what areas of the motor cortex would be larger?

A

Hands and face

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4
Q

what does the motor cortex encode?

A

movements not individual muscles

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5
Q

what is the main function of the primary motor cortex?

A

the execution of voluntary movement

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6
Q

is movement contralateral or ipsilateral to the motor cortex?

A

contralateral

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7
Q

what components of movement does the primary motor cortex encode?

A

force
direction
distance
speed

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8
Q

what is alien hand syndrome?

A

Involuntary, uncontrollable
movement of the upper extremity

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9
Q

what part of the brain is activated when you have alien hand syndrome?

A

contralateral primary motor cortex

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10
Q

what lobe is the premotor cortex in?

A

frontal lobe

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11
Q

what are the main functions of the premotor cortex?

A

motor planning
it selects the appropriate movements to perform

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12
Q

what part of the motor cortex are mirror neutrons in?

A

premotor cortex

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13
Q

how does the premotor cortex influence motor behaviour?

A

primarily via connections with the primary motor cortex

less commonly via axons projecting through the pyramidal tracts

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14
Q

what impairments may we se if there is a lesion to the premotor cortex?

A

speed and automaticity of reaching/grasping

sequential movements

gait and posture

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15
Q

what are the main functions of the supplementary motor area?

A

Programming complex sequences of
movements and coordinating bilateral movements

Selects movements based on previous experience

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16
Q

if you were learning how to play tennis and imagines yourself serving like Serena Williams, what part of the brain does this motor imagery?

A

supplementary motor area

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17
Q

what happens if there is a unilateral lesion of the SMA?

A

complete lack of contralateral movement and impaired ipsilateral movement

anti phase movement can be affected

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18
Q

what are anti phase movements?

A

Typing and playing the piano

tapping your head and rubbing your belly

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19
Q

where does intention of movement occur?

A

prefrontal cortex

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20
Q

where does motor planning occur?

A

premotor cortex

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21
Q

where does the execution of movement occur?

A

primary motor cortex

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22
Q

what is the somatotropin organization of the anterior horn of the spinal cord?

A

medial= proximal muscles
lateral= distal muscles

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23
Q

what is an interneuron/ local circuit neuron/

A

the “middle-man” that branches locally to innervate other neurons

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24
Q

are interneurons primarily inhibitory or excitatory?

A

inhibitory

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25
Q

do interneurons project ipsilaterally or contralaterally?

A

both!

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26
Q

what are the two types of interneurons?

A

long circuit
short circuit

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27
Q

what is the function of long circuit interneurons?

A

innervates proximal muscles for balance and postural control

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28
Q

what is the function of short circuit interneurons?

A

innervates distal muscles for fine motor control

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29
Q

how many levels do long circuit interneurons span?

A

multiple levels

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30
Q

can long circuit interneurons cross sides of the spinal cord?

A

yes it can cross bilaterally

31
Q

what part of the spinal cord can long circuit interneurons activate?

A

medial aspect of the anterior horn of spinal cord

32
Q

what is the functional relationship of long circuit interneurons?

A

bilateral control of postural muscles

balance

33
Q

how many levels does the short circuit interneurons span?

A

a few spinal levels (2-3)

34
Q

does the short circuit cross the midline of the spinal cord?

A

it is almost exclusively ipsilateral

35
Q

what part of the spinal cord does the short circuit interneurons activate?

A

lateral aspect of the anterior horn of the spinal cord

36
Q

what is the functional relationship of the short circuit interneurons?

A

allows for fine motor control

37
Q

where are the cell bodies of upper motor neurons located?

A

in supraspinal areas

38
Q

what two tracts can the descending motor pathway be divided into?

A

pyramidal and extrapyramidal tracts

39
Q

where does the pyramidal tract originate?

A

cerebral cortex

40
Q

what is the pyramidal tract responsible for?

A

skilled, voluntary movements of the limbs

41
Q

where does the extrapyramidal tract originate?

A

in the brainstem

42
Q

what is the extrapyramidal tract responsible for?

A

posture balance and gait

43
Q

where does the lateral corticospinal tract originate?

A

motor cortex, mostly M1

44
Q

where does 85% of the lateral corticospinal tract cross?

A

at the pyramidal decussation

45
Q

what is the destination of the lateral corticospinal tract?

A

lateral LMN of spinal cord

local short distance interneuron networks

46
Q

What is the function of the lateral corticospinal tract?

A

skilled, voluntary movement of the limbs

47
Q

If there is a lesion to the lateral corticospinal tract what side would be impaired?

A

contralateral side

48
Q

what is the origin of the anterior corticospinal tract?

A

motor cortex, mostly M1

49
Q

where does the remaining 15% of the corticospianl tract cross over?

A

in the spinal cord

50
Q

what is the destination of the anterior corticospinal tract?

A

it terminates bilaterally in the spinal cord

via long distance interneuron networks

51
Q

what is the function of the anterior corticospinal tract?

A

gross control of proximal postural muscles

52
Q

what are the impairments if there is a lesion to the anterior corticospinal tract?

A

minimal clinical effect

53
Q

what do most corticospinal fibres synapse directly with?

A

spinal interneurons that in turn synapse with LMNs

54
Q

what is the origin of the corticobulbar tract?

A

motor cortex

55
Q

what is the destination of the corticobulbar tract?

A

Most terminate bilaterally on local
circuit neurons in brainstem

LMN nuclei of cranial nerves

56
Q

what is the function of the corticobulbar tract?

A

Controls efferent activation of cranial
nerves

57
Q

if there is an injury to the corticobulbar tract (UMN) what would be the impairment?

A

Weakness in contralateral inferior facial muscles (left side of face) (Stroke)

58
Q

if there is an injury to the facial nerve (LMN) what would be the impairment?

A

Weakness in ipsilateral superior and
inferior facial muscles (entire left side of face)

59
Q

what is the origin of the extrapyramidal pathways?

A

various nuclei in the brainstem

60
Q

what is the destination of the extrapyramidal pathways?

A

Cross in antero-medial white matter of spinal cord

Innervates bilateral local long interneuron circuits

61
Q

what are the main functions of the extrapyramidal pathways?

A
  • Proximal muscles
  • Gait and postural stability
  • Recruits LMNs for sophisticated reflexes
  • Largely automatic control of movement
62
Q

is there function if the extrapyramidal pathways are damaged?

A

you can maintain some function

63
Q

what are the names of the extrapyramidal tracts?

A

rubrospinal
vestibulospinal
reticulospinal
tectospinal

64
Q

what is the function of the rubrospinal tracts?

A

flexor muscle tone and arm swinging

65
Q

what is the function of the vestibulospinal tract?

A

posture and balance

66
Q

what is the function of the reticulospinal tract?

A

Influence voluntary movements, gait, posture, reflexes, and excites/inhibits
muscle tone, sympathetic nervous system functions

67
Q

what is the function of the tectospinal tract?

A

eye/head motion

68
Q

are Parkinson’s and Huntington’s disease pyramidal or extrapyramidal?

A

extrapyramidal

69
Q

what are the clinical presentations of extrapyramidal tract disorders?

A

Slowing or loss of voluntary and automatic movements

Postural instability

Abnormal movement

70
Q

are extrapyramidal disorders typically bilateral or ipsilateral?

A

typically bilateral effects

71
Q

is the extrapyramidal tract movement volitional or automatic?

A

automatic

72
Q

is the pyramidal tract movement volitional or automatic?

A

volitional

73
Q

what distance local circuit neurons are with the extrapyramidal tract?

A

long distance local circuit neurons

74
Q

what distance local circuit neurons are with the pyramidal tract?

A

short distance local circuit neurons