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Neuro Part 2 > Week 5.2 > Flashcards

Week 5.2 Flashcards

1
Q

How is the anterior horn organized?

A
  • flexors dorsal and extensors ventral

- proximal medial and distal lateral

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2
Q

The medullar pyramids are a continuation of which spinal cord tract?

A

the corticospinal tract

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3
Q

What is the corticobulbar tract?

A

a tract of UMNs that terminate on LMNs in cranial nerve nuclei

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4
Q

The motor cortex is also known as Broadman’s area ___.

A

4

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5
Q

What is the purpose of descending neurons that reside in the somatosensory cortex?

A

modulate the sensitivity of sensory afferents (e.g. suppress and direct attention away from unimportant stimuli such as the feel of our clothes)

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6
Q

Descending neurons in the somatosensory cortex project where?

A

to dorsal column nuclei

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7
Q

What are extrapyramidal tracts?

A

those that, unlike the corticospinal tract, run outside the medullary pyramids

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8
Q

Describe the general features of extrapyramidal syndromes relative to a corticospinal syndrome?

A
  • rigidity
  • generalized hypertonus, mostly of flexors
  • normal reflexes
  • involuntary movements like chorea or tremor
  • absent babinski sign
  • only slight paralysis of voluntary movement
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9
Q

Describe the pathway of the rubrospinal tract.

A
  • originates in red nucleus
  • travels contralateral lateral column
  • terminates on interneurons in spinal cord
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10
Q

What is the function of the rubrospinal tract?

A

stimulates flexors and inhibits extensors is distal limb muscles

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11
Q

What is the function of the reticulospinal tract?

A
  • antigravity response

- stimulation of extensors

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12
Q

Describe the anatomy of the reticulospinal tract.

A
  • originates in reticular formation of medulla and pons

- pontine fibers travel in lateral column, medullar fibers in the ventral column

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13
Q

What is the function of the vestibulospinal tract?

A

antigravity response

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14
Q

Describe the anatomy fo the vestibulospinal tract.

A
  • originates from vestibular nuclei

- terminates on ipsilateral interneurons and LMNs in the anterior horn

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15
Q

What is the function of the tectospinal tract?

A

reflexive control of the neck in response to visual stimuli

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16
Q

Describe the anatomy of the tectospinal tract.

A
  • originates in superior colliculus
  • travels in contralateral ventral column
  • terminates on interneurons and LMNs in the cervical spinal cord
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17
Q

What is the general purpose of the spindle load compensation mechanism?

A

change muscle tone in response to changes in the external load

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18
Q

The spindle load compensation mechanism is mediated by what neurons?

A

spindle afferents

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19
Q

Spindle load compensation is best developed for which muscles?

A
  • postural muscles

- jaw muscles

20
Q

How does damage to the rubrospinal tract manifest?

A

little or no deficit if the corticospinal tract is intact

21
Q

How does damage to the reticulospinal tract manifest?

A

loss of righting reflexes

22
Q

How does damage to the vestibulospinal tract manifest?

A

loss of righting reflexes

23
Q

What causes decerebrate posture?

A

damage to the upper brain stem

24
Q

What causes decorticate posture?

A

damage to the corticospinal tract

25
Q

Describe decerebrate posture.

A
  • arms adducted and extended

- wrists pronated

26
Q

Describe decorticate posture.

A
  • arms adducted and flexed

- wrists and fingers flexed on chest

27
Q

What is a Jacksonian seizure?

A

a form of focal epilepsy in which the event travels across the homunculus, thus the seizure begins at the fingers and then travels more proximally

28
Q

What encodes the force of movement of muscles?

A

the firing rate of neurons in the motor cortex

29
Q

What information do UMNs in the primary motor cortex encode?

A
  • force
  • direction
  • velocity
  • joint position
30
Q

Describe the general pattern of information flow into the motor cortex.

A

Generally…
- basal ganglia, cerebellum, parietal cortex
- to the secondary motor areas and premotor cortex
- into the motor cortex
But BG, cerebellum, and parietal cortical areas can influence the motor cortex directly

31
Q

What is the function of the premotor cortex?

A
  • assembly of motor plans and programs

- and getting the individual ready to perform

32
Q

What is “motor set”?

A

a state of readiness for impending movement controlled primarily by the premotor cortex (e.g. do one action if light is blue, another if red, PMC will be very active as you wait)

33
Q

What is the function of the supplementary motor area?

A

program complex motor sequences

34
Q

Which motor area is extremely active when mentally rehearsing a potential movement?

A

the supplementary motor area

35
Q

What is the function of the parietal cortex in motor control?

A

selective attention to objects of motivational interest in the extrapersonal space

36
Q

How do parietal cortex area 5 and 7 differ in their control of motor activity?

A

area 5 directs arm movement while area 7 directs eye movement

37
Q

Neurons in areas 5 and 7 of the parietal cortex fire rapidly in response to what?

A

objects that are both of interest and obtainable entering the extra personal space

38
Q

Area 5 neurons can be thought of as issuing commands to the motor cortex for what?

A

manual exploration of objects of interest in the extra personal space

39
Q

Area 7 neurons can be thought of as issuing commands to where?

A

the frontal eye fields for eye movements to achieve and maintain fixation of objects of interest in extra personal space

40
Q

What part of the motor system is most commonly lesioned?

A

the internal capsule

41
Q

Lesions to the premotor cortex will cause what deficits?

A

impaired coordination and rapid movements

42
Q

Lesions to which part fo the motor system result in alien hand syndrome?

A

the supplementary motor area

43
Q

Lesions to the supplementary motor area will result in what sort of deficits?

A

speech difficulty and alien hand syndrome

44
Q

What is neglect?

A

the inability to respond to stimuli on the contralateral side of the body or the contralateral visual field

45
Q

Neglect syndrome is typically the result of a lesion located where?

A

the non-dominant parietal cortex

46
Q

Describe the effects of a parietal cortex lesion on motor activity.

A
  • neglect syndrome
  • difficulty manipulating or recognizing objects in the contralateral hand (apraxia and astereognosis)
  • errors in the accuracy of arm movements

Neuro Part 2 (18 decks)

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