3.19 Spinal Region 2 Flashcards

1
Q

spinal reflexes involve

A

interneurons

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2
Q

withdrawal reflex allows

A

capacity of interneuronal circuits to generate complex movements

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3
Q

What can elicit withdrawal movements?

A

afferent info from

  • skin
  • muscles
  • joints
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4
Q

reflexes: local sign

A
  • determines specificity of the movement pattern

- response depends on the site of stimulation

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5
Q

In withdrawal reflexes, why do the interneurons and collaterals of primary afferents relay information to other cord segments?

A

because muscles removing the part from the stimulation aren’t usually innervated by the same segment that received the afferent input

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6
Q

Inhibitory interneurons provide

A
  • reciprocal inhibition

- recurrent inhibition

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7
Q

Interneurons in inhibitory circuits contribute to

A

spinal cord motor function

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8
Q

reciprocal inhibition separates muscles into

A

agonists and antagonists

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9
Q

What prevents unwanted activity in antagonists when agonists are voluntarily recruited?

A

reciprocal inhibition interneurons

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10
Q

recurrent inhibition

A

opposite to reciprocal inhibition

  • inhibits agonists and synergists
  • disinhibition of antagonists
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11
Q

Renshaw cells

A

interneurons that produce recurrent inhibition

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12
Q

Renshaw cells are stimulated by

A

a recurrent collateral branch from the alpha motor neuron

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13
Q

What do Renshaw cells inhibit?

A

inhibit alpha motor neurons of synergists (and alpha motor neurons that give rise to collateral branches)

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14
Q

Renshaw cells do what to motor activity?

A

focus motor activity

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15
Q

loss of descending influence on Renshaw cell activity

A

may cause difficulty with fine motor control

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16
Q

What factors allow for bladder filling?

A
  • frontal cortex inhibits pontine urination center
  • sacral SC urination center (sympathetic and somatic signals)
  • may need corticospinal input with a powerful urge to urinate
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17
Q

bladder filling and sympathetic signals

A
  • relax bladder wall

- constrict internal sphincter

18
Q

bladder filling and somatic signals

A

constrict external sphincter

19
Q

corticospinal input with bladder filling

A

to LMN: cause contraction of pelvic floor muscles and external sphincter

20
Q

bladder emptying: factors

A
  • frontal cortex allows pontine urination center to activate

- parasympathetic signals from sacral spinal cord urination

21
Q

parasympathetic signals from sacral spinal cord urination center

A
  • contraction of bladder wall

- relaxation of internal sphincter

22
Q

What is the signal to empty the bowels?

A

stimulation of stretch receptors in the wall of the rectum

23
Q

What part of the SC vital for sexual function?

A

lower spinal cord

24
Q

erection of penis or clitoris controlled by

A

parasympathetic fibers from S2-S4

25
ejaculation elicited by
- sympathetic nerves from L1-L2 | - pudendal nerve
26
pudendal nerve cell bodies in
S2-S4
27
lesions in spinal region may interfere with these:
- segmental function - vertical tract function - both
28
segmental function: lesions
lesions interfere with neural function only at the level of the lesion
29
vertical tract function: lesions
loss of function below the level of the lesion
30
segmental signs
include - abn or lost sensation in a dermatomal distribution and/or - LMN neuron signs in a myotomal distribution
31
ascending tract signs
problems with regulation of - BP - sweating - bowel/bladder control
32
descending tract signs include
- paralysis - spasticity - muscle hypertonia
33
What happens if the lateral CST is interrupted?
Babinski's sign
34
All signs of damage to vertical tracts occur here
below level of the lesion
35
peripheral region lesions produce
deficits in peripheral nerve distribution
36
peripheral nerve lesions cause
- altered or lost sensation in peripheral nerve distribution | - decrease or loss of muscle power in peripheral nerve distribution
37
Are there vertical tract signs in peripheral region lesions?
NO
38
spinal region segmental signs occur when
nerve roots and/or spinal nerves are compromised
39
spinal region segmental signs include
- altered or lost sensation in a dermatome - decreased/lost muscle power in a myotome - decreased/lost phasic stretch reflex
40
spinal region vertical tract signs include:
- altered/lost sensation below lesion level | - altered/lost descending control of BP, pelvic viscera, and thermoregulation
41
UMN signs include
- decrease/loss in muscle power - spasticity - hypertonia - positive babinski/clonus (if lateral CST is involved)