Final Exam Flashcards

1
Q

What does the motor cortex consist of?

A
  • Primary motor cortex
  • Premotor area
  • Supplemental motor area
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2
Q

The Primary motor cortex has a __________ arrangement

A

Somatotropic

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3
Q

Greater than half of the primary motor cortex controls ___________

A

Hands & speech

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4
Q

Stimulating the primary motor cortex stimulates ____________ instead of ____________

A
  • movements

- contracting a single muscle

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5
Q

The ___________ area is the anterior and lateral portions of the primary motor area

A

Premotor

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6
Q

The premotor area projects to the _____________ and ___________

A
  • Primary motor cortex

- Basal ganglia

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7
Q

The supplemental area is superior to the premotor area and mainly lies in the _____________

A

Longitudinal fissure

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8
Q

What do the premotor and supplemental motor areas function in concert to do?

A
  • Attitudinal movements
  • Fixation movements
  • Positional movements of head and eyes
  • Background for finer motor control of arms/hands
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9
Q

The ____________ tract descends via the posterior limb of the internal capsule (lies between caudate and putamen)

A

Corticospinal

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10
Q

What does the corticospinal tract form?

A

Pyramids of the medulla

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11
Q

What do the corticospinal tract fibers do?

A
  • Some fibers cross midline & form the lateral corticospinal tract
  • Some fibers stay ipsilateral & form the ventral corticospinal tract
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12
Q

What is spinal preparation?

A
  • All tracts cut, cord completely isolated from brain

- Flaccidity (floppy paralysis)

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13
Q

What is decerebrate preparation?

A
  • Transection at mid collicular level

- Decerebrate rigidity (extensors tonically hyperactive)

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14
Q

What is decorticate preparation?

A
  • Destruction of the cerebral cortex
  • Decorticate spaciticity
  • Upper areas of reticular formation no longer under inhibitory cortical influence, therefore tonic excitation occurs
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15
Q

What is decorticate spasticity?

A
  • Removal or lesion of cerebral cortex
  • Seen in humans of the hemiplegic side after stroke
  • 60% of intracerebral hemorrhages
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16
Q

What does decorticate spasticity cause?

A
  • Loss of cortical inhibition of gamma efferent discharge mediated nu the medullary reticular formation
  • Small arteries in the internal capsule are prone to rupture or thrombosis
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17
Q

What is decerebration?

A
  • An experimental procedure useful for the study of reflexes
  • Transection of midbrain often at intercollicular level
  • Loss of sensation
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18
Q

What does decerebration alter?

A
  • Motor control
  • cortical descending pathways are interrupted
  • brain stem control remains intact
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19
Q

What specific effects does decerebration have?

A
  • Activity in some descending pathways: hyperactive
  • Flexion reflexes: suppressed
  • Stretch reflexes: exaggerated (selective excitation of gamma motor neurons)
20
Q

What does decerebration lead to?

A

Decerebrate rigidity

21
Q

What can happen with a spinal cord transection?

A

Spinal shock

22
Q

What specifically occurs with spinal shock?

A
  • Initially all cord functions, including spinal reflexes, are depressed (lack on tonic excitation from higher centers)
  • Spinal cord neurons gradually regains excitability (days/weeks)
  • Some spinal cord reflexes become hyperactive
  • Eventually results in a mass reflex
23
Q

What is a mass reflex?

A
  • Spinal cord becomes excessively active

- Causes flexor spasms and evacuation of bladder & colon

24
Q

What generally occurs with spinal shock?

A
  • Arterial blood pressure falls dramatically
  • All skeletal muscle reflexes integrated in the cord are blocked
  • Sacral reflexes for control of bladder and colon evacuation are suppressed
25
Q

What are the names of the reticular nuclei?

A
  • Pontine reticular nuclei

- Medullary reticular nuclei

26
Q

The pontine reticular nuclei transmit _______ signals via the ________________tract

A
  • Excitatory

- Pontine (medial) reticulospinal

27
Q

The pontine reticular nuclei stimulate the ______________

A

Axial trunk and extensor muscles (which support the body against gravity)

28
Q

The pontine reticular nuclei receive stimulation from the _________ & _________

A
  • Vestibular nuclei

- Deep nuclei of the cerebellum

29
Q

The pontine reticular nuclei have a high degree of ___________

A

Natural excitability

30
Q

The medullary reticular nuclei transmit ________ signals via the ___________ tract

A
  • Inhibitory

- Medullary (lateral) reticulospinal tract

31
Q

The medullary reticular nuclei inhibit the ___________

A

Axial trunk and extensor muscles (which support the body against gravity)

32
Q

The medullary reticular nuclei receive strong input from the ________

A
  • Cortex
  • Red nucleus
  • Other motor pathways
33
Q

The medullary reticular nuclei allows___________________

A

Tone to be increased or decreased (depending on function needing to be performed)

34
Q

Summarize the ventral corticospinal tract

A
  • Descending pathway
  • Ipsilateral
  • Medial motor system
  • Controls mainly axial and girdle muscles
35
Q

Summarize the Reticulospinal tracts

A
  • Consists of the Pontine & Medullary reticualr formations
  • Descending pathway
  • Ipsilateral
  • Medial motor system
  • Controls mainly axial and girdle muscles
36
Q

Summarize the Vestibulospinal tracts

A
  • Origin from lateral vestibular nucleus to mainly extensors
  • Descending pathway
  • Ipsilateral
  • Medial motor system
  • Controls mainly axial and girdle muscles
37
Q

Summarize the Lateral Corticospinal tract

A
  • Descending pathway
  • Contralateral
  • Lateral motor system
  • Controls more distal muscles of limbs
38
Q

Summarize the Rubrospinal tract

A
  • Innervates mainly flexors
  • Descending pathway
  • Contralateral
  • Lateral motor system
  • Controls more distal muscles of limbs
39
Q

Summarize the Tectospinal tract

A
  • Innervates cervical musculature only
  • Superior colliculus- orienting reactions
  • Descending pathway
  • Contralateral
  • Medical motor system
40
Q

The primary motor cortex has a _______________ arrangement

A

Vertical columnar

41
Q

The primary motor cortex functions as an _______________

A
  • Integrative processing system

- Stimulation of 50-100 pyramidal cells to achieve muscle contraction

42
Q

What are the two types of output for pyramidal cells?

A
  • Dynamic signals

- Static signals

43
Q

What do dynamic signals do?

A

Excessively excited at the onset of contraction to initial muscle contraction

44
Q

What do static signals do?

A

Fire at a slower rate to maintain contraction

45
Q

What are the phases of voluntary movement?

A
  1. Planning & programming phase

2. Execution phase

46
Q

What are the steps involved in voluntary movement?

A
  1. Signals for movement originate in the sensory association cortex
  2. Go directly or indirectly via Basal ganglia & Ceerebrocerebellum
  3. Go to primary motor cortex
    4a. Go to spinal cord
    4b. Go to spinocerebellum
    * Feedback from periphery goes to spinocerebellum and then to primary motor cortex
47
Q

What is electromyography (EMG)?

A
  • The electrical activity within an accessible muscle can be recored via insertion of a needle electrode into it
  • Patterns of activity at rest and during contraction have been characterized under normal and abnormal conditions