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Neuro > Peripheral Nerves > Flashcards

Peripheral Nerves Flashcards

1
Q

What are the layers of a peripheral nerve (3)

A
  1. Endoneurium
  2. Perineurium
  3. Epineurium
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2
Q

What is the endoneurium

A

CT that surrounds axons schwann cells and other endoneurial components

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3
Q

What is the perineurium

A

Dense CT that forms the fascicles

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4
Q

How many layers thick is the perineurium

A

Up to 15 layers

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5
Q

What is the perineurium made of

A

Type I and II collagen

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6
Q

What is the epineurium

A

CT that surrounds nerve fascicles

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7
Q

What are the 2 parts of the epineurium

A
  1. Epifasicular

2. Interfascicular

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8
Q

What is the epifasicular

A

Surrounds the entire nerve (outer layer)

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9
Q

What is the interfascicular

A

Separates the nerve fascicles

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10
Q

How is the perineurium attached to the epineurium

A

Loosely attached

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11
Q

What does the perineurium being loosely attached to the epineurium allow for

A

Sliding to occur between fascicles

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12
Q

True or False:

There are arteries in nerves

A

True

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13
Q

What happens to the nerve at places where it spilts

A

The nerve becomes stiff and may not slide well

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14
Q

What does movement of the nervous system do (3)

A
  1. Prompts the flow of blood throughout the nerve
  2. Prompts removal of waste
  3. Stimulates axoplasmic flow in the axon
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15
Q

What are the 2 types of axoplasmic flow in an axon

A
  1. Anterograde

2. Retrograde

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16
Q

Do the capillaries in the nerves have smooth muscle

A

No

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17
Q

What does the capillaries not having smooth muscle require

A

The nerve needs to be moved to pump blood throughout the nerves

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18
Q

Are there lymphatics in nerves

A

No

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19
Q

What does not having lymphatics in nerves make it hard to do

A

Get rid of swelling

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20
Q

What is the direction and magnitude of nerve excursion dependent upon

A

The relationship between the nerve and the axis of rotation in the moving joint

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21
Q

Where does nerve excursion first occur

A

The site immediately adjacent to the moving joint

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22
Q

What is convergence

A

Nerve tissue is moving toward the joint causing motion

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23
Q

What is divergence

A

Nerve tissue moving away from the joint causing motion

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24
Q

When does convergence occur

A

When the nerve is tensioned at the joint moving

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25
Q

When does divergence occur

A

When the nerve is slackened at the joint moving

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26
Q

Going from wrist flexion to wrist extension what occurs to the median and ulnar nerves

A

They are both tensioned so convergence occurs

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27
Q

Going from elbow flexion to elbow extension what occurs to the median and ulnar nerves

A

Median nerve is tensioned so convergence occurs

Ulnar nerve is slackened so diverengce occurs

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28
Q

True or False:

Nerves try to move back to the resting position of the nerve

A

True

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29
Q

Are myelin and CT able to stretch and fold

A

Yes’m

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30
Q

True or False:

Nerves are a lot of CT with small amounts of fascicles within them

A

True

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31
Q

Where is it apparent that nerves are full of CT and small amounts of fascicles

A

The cubital tunnel

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32
Q

What does tensile stress lead to in nerves

A

Elongation of the nerve (strain)

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33
Q

What occurs to the nerve in addition to the elongation

A

Transverse contraction in the center of the nerve occurs

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34
Q

What does the transverse contraction result in

A

Increased intraneural pressure

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35
Q

What does the amount of strain placed on the nerve depend on

A

Its relationship to the axis of rotation in the moving joint

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36
Q

Where does the most movement and strain occur during movement

A

At the joint moving

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37
Q

True or False:

Sliders put limited to no strain on the nerve

A

True

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38
Q

True or False:

Tensioners put more strain on the nerve

A

True

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39
Q

What does a steep slope on the stress strain curve indicate

A

That the tissue isn’t very compliant

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40
Q

What amount of repetitive strain can nerves tolerate

A

6-8%

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41
Q

When do you start to see damage in a nerve due to the strain

A

11%

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42
Q

What can peripheral nerve injuries be classified as (2)

A
  1. Mononeuropathy

2. Polyneuropathy

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43
Q

What is mononeuropathy

A

Single nerve issue

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44
Q

What is polyneuropathy

A

Multiple nerve problem

45
Q

What are the 3 types of damage that occur to nerve

A
  1. Traumatic myelinopathy
  2. Traumatic axonopathy
  3. Severance
46
Q

What is the pathology of a traumatic myelinopathy

A

Demyelination

47
Q

What is the pathology of a traumatic axonopathy

A

Axonal damage

48
Q

What is the pathology of severance

A

Axonal damage and demyelination

49
Q

What is the typical recovery of a traumatic myelinopathy

A

Complete and rapid recovery

50
Q

What is the typical recovery of a traumatic axonopathy

A

Slow by regrowth of axons but good prognosis because Schwann cells are usually intact

51
Q

What is the typical recovery of severance

A

Typically slow with incomplete recovery

52
Q

True or False:

Myelin is able to regenerate as long as the nucleus is still intact in the Schwann cell

A

True

53
Q

What causes a traumatic axonopathy

A

Nerve on tension for a long period of time

54
Q

In animal models what amount of prolonged lengthening lead to ischemia in the sciatic nerve

A

8%

55
Q

In the animal model why was the reperfusion of the nerve potentially more damaging secondary to hyperemic blood flow

A

Because the amount of blood in the nerve is increased more than normal leading to increased pressure

56
Q

What does the prolonged pressure from the increased fluid lead to

A

Damage to myelin because there are no lymphatics

57
Q

What does acute compression of 20-30 mmHg interfere with in a nerve

A

Venous blood flow

58
Q

What does acute compression of 35-50 mmHg cause

A

Reduced capillary flow

59
Q

What does acute compression of 70 mmHg cause

A

Complete ischemia

60
Q

What does chronic compression lead to in a nerve (4)

A
  1. Epineural fibrosis
  2. Demyelination
  3. Axonal degradation
  4. Perineural thickening
61
Q

What does injury to peripheral nerves lead to

A

Wallerian degeneration

62
Q

What is Wallerian degeneration

A

Everything distal to the injury dies and is broken down and taken up by the body

63
Q

What happens to the proximal end of the damaged peripheral nerve

A

Upregulation of proteins from the cell body trying to recapture the lost end

64
Q

When a nerve is severed what happens to the nerve endings

A

They retract away from the site of injury

65
Q

When does Wallerian degeneration occur

A

When axons are injured

66
Q

What does blockage of axonal transport do

A

Limits the flow of neurotrophic factors

67
Q

What occurs due to the increased disruption of axonal transport

A

Axonal spheroids grow

68
Q

What is an axonal spheroid

A

Build up of substances in an axon

69
Q

What occurs once the axonal spheroid is formed

A

Wallerian degeneration leaving an end bulb on the proximal axon

70
Q

Is the end bulb myelinated or not

A

Not myelinated

71
Q

True or False:

There is a large deposition of Na+ channels at the end bulb of damaged nerves

A

True

72
Q

What does the large deposition of Na+ channels lead to

A

Spontaneous firing seen in people with chronic pain

73
Q

Does the nerve need to be severed to have nerve death

A

Nope the terminal end could not get the appropriate nutrients due to a blockage which leads to a build up of fluid causing an end bulb

74
Q

True or False:

Damage of a nerve can be due to constant use

A

True (carpal tunnel)

75
Q

True or False:

Na+ channels accumulate at end bulbs and areas of demyelination

A

True

76
Q

What does the accumulation of Na+ channels in the regions of demyelination and end bulbs likely to occur due to

A

Abnormal trafficing

77
Q

What does the accumulation of Na+ channels cause

A

Potential for ectopic discharge and pacemaker capability in neuropathic pain

78
Q

What is ectopic discharge

A

When nerve stimulation occurs at a sight other than the normal site of stimulation

79
Q

When does spontaneous ectopic firing in an injured nerve begin in myelinated axons

A

As early as 16 hours

80
Q

When does spontaneous activity in unmyelinated axons that are damaged appear

A

Weeks following the initial injury

81
Q

What fibers have spontaneous firing (2)

A
  1. A-beta

2. A-delta

82
Q

What is nociceptive pain

A

Pain due to stimulation of nociceptors largely dominated by C-fibers

83
Q

What is neuropathic pain

A

Pain due to A-beta and A-delta fibers

84
Q

When do C-fibers kick in during neuropathic pain

A

Much much later

85
Q

True or False:

Damage to axons leads to ectopic firing

A

True

86
Q

What happens when we activate 2nd messengers for a long time

A

Adaption over time

87
Q

True or False:

Substance P is upregulated in large diameter dorsal root ganglion neurons following an axotomy

A

True

88
Q

True or False:

Phenotypic switching is likely the reason A-beta fibers contribute to neuropathic pain

A

True

89
Q

Know chart about sequence of severed nerves

A

OKIE DOKIE

90
Q

What are the negative signs and symptoms of peripheral nerve injury

A

Decreased nerve conduction velocity

91
Q

Why is there decreased nerve conduction velocity

A

Demyelination occurs leading to no saltatory conduction

92
Q

Get EMG slide cleared up by Dr. Brown

A

OK

93
Q

What types of nerves have the ability to regenerate

A

Peripheral nerves

94
Q

How long can a peripheral nerve take to heal

A

Several months

95
Q

What needs to occur for axonal regeneration

A

Wallerian degeneration

96
Q

Even though peripheral nerves can regenerate there is no guarantee the nerve will grow back completely

A

True

97
Q

What does injury to the peripheral nerve do

A

Stimulate a number of signaling cascades that stimulate the upregulation of regeneration related genes

98
Q

How much does a peripheral nerve grow a day

A

1 mm/day

99
Q

True or False:

Peripheral nerve injuries stimulate second messengers

A

True

100
Q

What does the stimulation of second messengers stimulate

A

Transcription of proteins and other substances that influence nerve growth

101
Q

True or False:

Myelin growth is rapid

A

True

102
Q

When does Wallerian degeneration occur in a completely severed nerve

A

3-5 days

103
Q

What happens if a neuroma forms after injury

A

You will not get reconnection of the nerve

104
Q

What do sliders increase

A

Axonal flow

105
Q

What causes faster regrowth of nerves

A

Endurance training

106
Q

True or False:

Resistance training leads to slower regrowth of nerves

A

True

107
Q

What do tensioners do

A

Allows us to elongate tissue potentially leading to realignment of tissues

108
Q

True or False:

The outcomes of resistance and endurance training eventually came out to be the same

A

True

109
Q

Motivation

A

Good luck dude you are almost done for the summer!! Keep pushing and you will make it through!

Neuro (15 decks)

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