3.19 Spinal Region Flashcards

1
Q

rootlets

A

small groups of axons sending information to the periphery

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2
Q

ventral root

A

combo of ventral rootlets

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3
Q

dorsal root

A
  • contains sensory axons bring info to the spinal cord

- enters posterolateral SC via rootlets

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4
Q

How is the SC organized?

A

segmentally

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5
Q

How is each segment of SC connected to a specific region of the body?

A

by axons traveling through a pair of spinal nerves

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6
Q

What indicates segments?

A

connections of nerve rootlets to exterior of the cord

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7
Q

What do spinal nerves carry?

A

all motor and sensory axons of a single spinal segment

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8
Q

Where are the spinal nerves in the c-spine?

A

above corresponding vertebrae (except 8th)

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9
Q

Where do the spinal nerves run in thoracic and lumbar spine?

A

below corresponding vertebrae

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10
Q

dorsal horn processes:

A

sensory info

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11
Q

lateral horn processes:

A

autonomic info

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12
Q

ventral horn processes:

A

motor info

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13
Q

most gray matter in SC composed of

A

interneurons

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14
Q

interneuron locations

A
  • cells entirely in gray matter AND

- cells with axons that travel to different levels of the cord

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15
Q

meninges

A
  • layers of connective tissue that surround the cord

- continuous with meninges that surround the brain

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16
Q

arachnoid mater separated from pia by

A

CSF in the subarachnoid space

17
Q

What causes stretching of the lumbosacral roots?

A

hip flexion: produces anterior mvt of cauda equina

18
Q

effect of extension/lateral flexion on c-spine

A

increased intervertebral foramen pressure at all cervical levels

19
Q

effect of physiologic motions on vertebral canal

A

don’t significantly change size in people with normal vertebral canals

20
Q

What neck movement increases cervical nerve root s/s?

21
Q

afferent and descending info converge on

A

the same spinal interneurons

22
Q

What acts together to produce goal-oriented movements?

A
  • reflexes

- voluntary control

23
Q

What do reflexes depend on?

A
  • environmental context
  • task

not hardwired

24
Q

What does spinal circuitry provide by integrating volleys of peripheral, ascending, and descending inputs?

A
  • modulation of sensory information
  • coordination of movement patterns
  • autonomic regulation
25
These circuits integrate activity from all sources and adjust output of LMN
interneuronal circuits
26
What do interneurons coordinate when a limb moves?
activity in all the muscles
27
What determines whether a single alpha motor neuron will fire?
Summation of activity at 20,000 to 50,000 synapses determines whether an alpha motor neuron will fire.
28
What is a stepping pattern generator?
adaptable neural networks that produce rhythmic output
29
How does a stepping pattern generator contribute to stepping?
activating LMNs, causing alternating flexion and extension at the hips and knees
30
Normal activation of stepping pattern generators occurs when
the person voluntarily sends signals from the brain to the stepping pattern generators (SPGs) in the spinal cord to initiate walking.
31
When walking, __________ produces different responses, depending on the phase of the gait cycle
electrical stimulation to a single point on the foot
32
stepping pattern generation If stimulus occurs at the onset of swing phase, this activity increases
tibialis anterior activity
33
stepping pattern generation If stimulus occurs at the end of the swing phase, this happens
- tibialis anterior activity decreases | - antagonist muscle activity increases