3.21 Spinal Region Lecture 2 Flashcards

1
Q

What do radicular arteries arise from?

A

thoracic and abdominal aortae

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2
Q

Each radicular artery gives rise to

A

one spinal artery (anterior spinal artery)

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3
Q

What happens to the 2 anterior spinal arteries?

A
  • fuse and run in anterior median fissure

- run the entire length of SC

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4
Q

What supplies the anterior 2/3 of the SC?

A

branches of anterior spinal arteries

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5
Q

What supplies the posterior 1/3 of SC?

A

PICA

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6
Q

What happens to the PICA to supply the SC?

A

PICA
» 2 posterior spinal arteries
» proceed along dorsal rootlet attachments

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7
Q

Where are the dorsal rootlet attachments?

A

in posterolateral sulci

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8
Q

Does fusion occur with posterior blood supply?

A

nope

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9
Q

T12 significance with SC blood supply

A
  • great radicular artery

- supplies lumbosacral in addition to everything else

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10
Q

How does venous drainage occur?

A
  • via radicular veins

- drains into epidural venous plexus

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11
Q

functions of SC

A
  • exchanging info from other segments via columns

- exchanging info from periphery

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12
Q

What is the “key” to SC that helps with modulation?

A

interneurons

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13
Q

3 things interneurons help with

A
  • stepping pattern generators
  • reflexes
  • inhibitory circuits
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14
Q

function of inhibitory circuits

A

modulation of fine motor activity

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15
Q

What is a stepping pattern generator a subtype of?

A

central pattern generator

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16
Q

What do stepping pattern generators do?

A

help keep normal cadence/rhythm when you walk

17
Q

stepping pattern generators in lower thoracic/lumbar regions

A

help with locomotion

18
Q

stepping pattern: external stimulation

A

electrically stimulating LMNs

- no cortical input necessary

19
Q

What produces stepping pattern generators?

20
Q

initial decision to move comes from

A

motor cortex

motor planning regions

21
Q

adaptability of stepping pattern generators to different scenarios (ex.)

A

think feet on treadmills going different directions

22
Q

Are stepping pattern generators sufficient for walking? Why or why not?

A
  • no

- higher neural control for purposeful movements

23
Q

What is necessary for activation of interneuron circuits for stepping pattern?

A

UMN activation

24
Q

overall action of UMN with step pattern

A

fires to both flexor and extensor motor neurons

  • extensors contract
  • flexors inhibited

reciprocal inhibition

25
Interneuron activity in stepping pattern
- causes reciprocal inhibition - get a refractory period - cycle repetition
26
refractory period of interneurons: implication
- flexors now free to contract because they aren't getting inhibition - inhibition of extensors happen now as well
27
UMN contribution to walking
- doesn't have to act much | - initial firing due to decision made
28
How does sensory input come into play with stepping pattern gen?
GTO helps with proprioception and appropriate level of firing of LMN to muscles
29
- inhibition of antagonist | - activation of agonist
reciprocal inhibition
30
- inhibition of agonist | - activation of antagonist
recurrent inhibition
31
When might reciprocal inhibition fail to occur?
when anxious (makes you really tired!)
32
What cells allow recurrent inhibition?
Renshaw cells
33
What are Renshaw cells?
- branches of alpha motor neurons | - feed back and inhibit themselves
34
Renshaw cells and inhibition: example
- playing piano and fine motor control | - keeps from overshooting notes
35
reciprocal and recurrent inhibition work _______
simultaneously