3.21 Spinal Region Lecture 2 Flashcards Preview

7303 Neuroanatomy > 3.21 Spinal Region Lecture 2 > Flashcards

Flashcards in 3.21 Spinal Region Lecture 2 Deck (35):
1

What do radicular arteries arise from?

thoracic and abdominal aortae

2

Each radicular artery gives rise to

one spinal artery (anterior spinal artery)

3

What happens to the 2 anterior spinal arteries?

- fuse and run in anterior median fissure
- run the entire length of SC

4

What supplies the anterior 2/3 of the SC?

branches of anterior spinal arteries

5

What supplies the posterior 1/3 of SC?

PICA

6

What happens to the PICA to supply the SC?

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

7

Where are the dorsal rootlet attachments?

in posterolateral sulci

8

Does fusion occur with posterior blood supply?

nope

9

T12 significance with SC blood supply

- great radicular artery
- supplies lumbosacral in addition to everything else

10

How does venous drainage occur?

- via radicular veins
- drains into epidural venous plexus

11

functions of SC

- exchanging info from other segments via columns
- exchanging info from periphery

12

What is the "key" to SC that helps with modulation?

interneurons

13

3 things interneurons help with

- stepping pattern generators
- reflexes
- inhibitory circuits

14

function of inhibitory circuits

modulation of fine motor activity

15

What is a stepping pattern generator a subtype of?

central pattern generator

16

What do stepping pattern generators do?

help keep normal cadence/rhythm when you walk

17

stepping pattern generators in lower thoracic/lumbar regions

help with locomotion

18

stepping pattern: external stimulation

electrically stimulating LMNs
- no cortical input necessary

19

What produces stepping pattern generators?

SC

20

initial decision to move comes from

motor cortex
motor planning regions

21

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

think feet on treadmills going different directions

22

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

- no
- higher neural control for purposeful movements

23

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

UMN activation

24

overall action of UMN with step pattern

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