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Physiology > Corticomotor system > Flashcards

Corticomotor system Flashcards

1
Q

What is the first event of the three that preceded voluntary motor movement?

A

Perceptual mechanisms generate a sensory model of the external world and a person’s position in the environment

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2
Q

What is the second event of the three that preceded voluntary motor movement?

A

Cognitive processes use the internally generated model to decide on a course of action

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3
Q

What is the third event of the three that preceded voluntary motor movement?

A

The selected motor plan is conveyed to the neural areas responsible for implementation of the plan

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4
Q

What are the areas of the motor cortex?

A
  1. Primary motor cortex
  2. Supplementary/motor cortex
  3. Cingulate motor cortex
  4. Frontal eye fields
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5
Q

What is the function of the reticulospinal tract?

A

are medial system motor pathways for control of axial and proximal muscles

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6
Q

What is the function of the rubrospinal tract?

A

part of lateral system motor pathways to control mainly distal and proximal muscles of the upper extremity. (monkeys)

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7
Q

Where does the red nucleus receives most of its innervation from?

A

cerebellum and primary motor cortex

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8
Q

The rubrospinal tract go where?

A

Flexors of the hands

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9
Q

Which lobe is the frontal eye field located in?

A

Frontal lobe

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10
Q

Neurons in the frontal eye field will collaborate with cells where to control eye movement?

A

Superior colliculus to PPRF

OR

straight to PPRF (horizontal gaze centers)

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11
Q

What is the route of the motor system innervation?

A

Parietal, premotor/supplementary cortex

Primary motor cortex

Brainstem

Spinal cord

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12
Q

Corticobulbar tract = what tract?

A

Corticonuclear (same thing, different name)

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13
Q

What is significant about the way the upper and lower parts of the facial nucleus is innervated by UMNs?

A

Upper part get bilateral projections

Lower part only contralateral

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14
Q

True or false: Corticorubral fibers and corticoreticular fibers are also part of the corticonuclear tracts

A

True

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15
Q

Corticonuclear fibers pass through what part of the internal capsule on their way to the brainstem? What is the next part?

A

Genu, then crus cerebri

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16
Q

Motor control of the extraocular eye muscles is partially via a projection from what two cortical areas?

A

the frontal and parietal motor eye fields of the cortex

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17
Q

the frontal and parietal motor eye fields of the cortex send projections where to innervate the eyes?

A

the horizontal and vertical gaze centers of the reticular formation

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18
Q

What are the two ways of smiling?

A

Pyramidal system

RF

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19
Q

What is the pathway for the pyramidal smiling?

A

Cortex to pyramids to facial nucleus

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20
Q

What is the non-pyramidal pathway for smiling?

A

Forebrain/hypothalamus to the facial nucleus

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21
Q

Where does the corticospinal tract cross?

A

Lateral crosses in the medulla

Anterior crosses at the spinal cord level

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22
Q

What percent of fibers of the corticospinal tract cross in the medulla, to form the lateral corticospinal tract?

A

90%

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23
Q

Where do the fibers of the lateral corticospinal tract synapse (on what neurons)?

A

Anterior horn nuclei to distal limbs for fractionated movements

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24
Q

What percent of fibers of the corticospinal tract do not cross in the medulla, but instead stay anteriorly to form the lateral corticospinal tract?

A

10%

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25
Q

What is the function of the anterior corticospinal tract?

A

Motor innervation to the trunk, neck, and shoulder

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26
Q

True or false: the corticospinal tract is only involved in motor functions

A

False–has sensory, to emphasize movement

27
Q

What is the origin of the lateral corticospinal tract?

A

Frontal cortex, and somatosensory cortex

28
Q

What is the origin of the anterior corticospinal tract?

A

only the motor cortex

29
Q

What type of movement is the lateral corticospinal tract necessary for?

A

Fractionated movements of the hand and fingers

30
Q

Why can we not (physically) perform experiments on humans to cut the corticospinal tract?

A

Intermingles with the rubrospinal tract, thus no way to isolate it

31
Q

How is the motor cortex fibers organized?

A

According to a given task, rather than a specific muscle

32
Q

Can somatotopic organization of the motor cortex change?

A

yes

33
Q

What artery gets the leg area of the primary motor cortex?

A

anterior cerebral

34
Q

What artery supplies the trunk, hand, and face area of the primary motor cortex?

A

Middle cerebral

35
Q

Lesions restricted to the primary motor cortex can cause what?

A

Persistent hypotonia or spasticity if other cortical areas involved

36
Q

What are the arteries that supply the internal capsule (branches of the middle cerebral)?

A

Lenticulostriate

37
Q

What is paresis?

A

Weakness of voluntary muscle

38
Q

What is the role of the premotor area?

A

Goal directed movement that requires sensory information about the environment

39
Q

What a mirror neurons?

A

Neurons in the premotor area that might encode the intentions and actions of others and participate in imitation learning

40
Q

What are the functions of the premotor cortex compared to the supplementary motor cortex?

A

PM more important for movements activated or guided by external stimuli

41
Q

What is the role of the supplementary motor cortex? (2)

A

Planning or preparing for sequential motor acts.

Coordinating movements from each side of the body

(especially those initiated or controlled by internal, remembered or self-determined stimuli)

42
Q

What area of the brain has been implicated in the inability to start activities like walking parkinsons?

A

Putamen

43
Q

Do lesions of the SMC produce paralysis?

A

No, but do cause problems in initiating or suppressing movement

44
Q

What is the function of the frontal eye field?

A

INfluences eye movements through projections to the brainstem vertical and horizontal gaze centers and the superior colliculus

45
Q

What is the input to the frontal eye field?

A

visual association cortex and basal ganglia and thalamic relays about the location of a visual target

46
Q

What are the three projections that the frontal eye field sends off to help eye movement?

A

projections to the brainstem vertical and horizontal gaze centers and the superior colliculus.

47
Q

What is the input to the FEF?

A

from visual association cortex and basal ganglia and thalamic relays

48
Q

What is the effect of a lesion in the FEF?

A

Permanent deficit in the ability to make saccades that are not guided by an external target

Cannot voluntarily direct their eyes away from a stimulus in the visual field

49
Q

Where do the cortical influence over eye movements go (which nucleus) to have an effect on the eyes?

A

Pontine RF

50
Q

What are saccades?

A

Small movements of the eye

51
Q

What part of the brain is involved in the reflexive saccades?

A

Superior colliculus

52
Q

What is Brown-sequard syndrome?

A

Hemisection of the spinal cord

53
Q

Fasciculations and fibrillations are characteristics of UMNs or LMN lesions?

A

LMNs

54
Q

If there is a brainstem lesion to the UMN in the spinal cord which side will be affected?

A

Contralateral

55
Q

If there is a brainstem lesion to the LMN in the spinal cord which side will be affected?

A

Ipsilateral

56
Q

What are the deficits of Brown-Sequard syndrome ipsilateral to the lesion?

A

Loss of fine touch, UMN symptoms below lesion, LMN signs at level of lesion

57
Q

What are the deficits of Brown-Sequard syndrome contralateral to the lesion?

A

Loss of pain and temp sensation

58
Q

UMN lesion will produce what symptoms in the Babinski response?

A

Upgoing response (extension of the great toe, and flaring of the other toes)

59
Q

A lesion to the corticospinal tract / corticonuclear tract origin will produce weakness where?

A

Facial weakness ipsilateral

Limb paralysis contralateral

60
Q

What is alternating hemiplegia?

A

is caused by pontine lesions which involve corticospinal tract fibers and fibers from the abducens nucleus.

61
Q

What type of lesion will affect one entire half of the body?

A

Hemispheric lesion

62
Q

What type of lesion will affect ipsilateral face and contralateral side of the body?

A

Brainstem lesion

63
Q

Lesions restricted to the primary motor cortex cause what symptoms?

A

Persistent hypotonia

Physiology (75 decks)

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