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Flashcards in PNS lecture Deck (27)
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1
Q

what does a NCV test measure?

A

used to measure the speed of electrical conduction through a nerve

2
Q

If there is a deficit, what does this NCV test help with determining?

A

it can help determine if any nerve damage or destruction exists.

3
Q

what is the first step in measuring NCV?

A

use the median nerve and test the time it takes for a stimulus to traverse the nerve along two different distances and get the difference between them (T2-T1)

4
Q

what is the second step in measuring NCV?

A

Divide the distance between the two locations (D/T2-T1) to find the actual conduction velocity

5
Q

In testing motor where do you stick the stimulators and recorders?

A

recording electrode is placed on the skin over the abductor pollicis muscle
nerve then receives mild electrical stimulation at the level of the cubital fossa, and the time is recorded until the abductor pollicis muscle contracts

6
Q

In testing sensory where do you stick the stimulators and recorders?

A

skin of the finer may receive stimulation with recording electrodes placed near the nerve at the wrist and cubital fossa.

7
Q

If there is a lesion of the motor neuron soma then what observations should be seen?

A

little/no change in motor

no change in sensory

8
Q

if there is a lesion of the peripheral nerve what observations should be seen?

A

Compression –> slowing of motor and sensory
Demyelination –> marked slowing of motor and sensory
Mild Axonal Degeneration –> slight/no reduction

9
Q

If there is a lesion of the NMJ and or muscle what observations should be seen?

A

No change in sensory or motor

10
Q

Peripheral nerve damage develops at the innermost structures first and works toward the outermost structures, name the structures.

A

Most Vulnerable to Damage: Axon –> Endoneurium –> perineurium —> epineurium

11
Q

what is carpal tunnel syndrome?

A

compression of the median nerve at the wrist due to swelling wrist tendons which eventually compress the nerve. (reduction in tunnel size)

12
Q

what are some of the symptoms associated with carpel tunnel syndrome?

A

pain, weakness, and numbness in the hand and wrist occur and radiate up the arm

13
Q

who are most at risk to developing carpal tunnel syndrome?

A

middle aged females (Esp due to over use)

14
Q

what does Axotomy mean?

A

after nerve injury where axons are ruptured/cut, several mechanisms might occur

15
Q

what is wallerian degeneration?

A

degeneration of the distal part of the axon ( terminal degeneration)

16
Q

what is the anterograde transneural degeneration

A

degeneration of the distal nerve

17
Q

what is retrograde transneural degeneration?

A

degeneration of the proximal nerve

18
Q

After dissection of a peripheral nerve, what happens?

A

terminal end sprouts

19
Q

what happens after terminal end sprouting?

A

one of the sprouts will find the guide tube created by Schwann cells and the axon will continue to grow

20
Q

What is the growth of the peripheral nerve facilitated by?

A

nerve growth factor (schwann cells), laminin and adhesion molecules

21
Q

Once the new axon is grown what is the final step?

A

schwann cells will redevelop and remyelinate the newly grown axon

22
Q

why does regeneration/remyelination in the CNS not occur?

A

oligodendrocytes do not release nerve growth factor

23
Q

what is Gliosis?

A

astrocytes multiply in regions of trauma which create glial scars and stop the development of axonal sprouts

24
Q

what is released in the CNS that opposes axonal regeneration in adults?

A

inhibitory chemical messengers are released in the CNS

25
Q

following nerve damage, what happens to motor axons?

A

motor axons regenerate and form new NMJs usually in the same place as before.

26
Q

what is responsible for differentiating the growth cone into the nerve terminal?

A

basal lamina

27
Q

What are the different isoforms of laminin?

A

Laminin 11 –> seen in synaptic basal lamina

Laminin 2 –> seen in the extrasynaptic basal lamina