Peripheral Nerves Flashcards
(109 cards)
1
Q
What are the layers of a peripheral nerve (3)
A
- Endoneurium
- Perineurium
- Epineurium
2
Q
What is the endoneurium
A
CT that surrounds axons schwann cells and other endoneurial components
3
Q
What is the perineurium
A
Dense CT that forms the fascicles
4
Q
How many layers thick is the perineurium
A
Up to 15 layers
5
Q
What is the perineurium made of
A
Type I and II collagen
6
Q
What is the epineurium
A
CT that surrounds nerve fascicles
7
Q
What are the 2 parts of the epineurium
A
- Epifasicular
2. Interfascicular
8
Q
What is the epifasicular
A
Surrounds the entire nerve (outer layer)
9
Q
What is the interfascicular
A
Separates the nerve fascicles
10
Q
How is the perineurium attached to the epineurium
A
Loosely attached
11
Q
What does the perineurium being loosely attached to the epineurium allow for
A
Sliding to occur between fascicles
12
Q
True or False:
There are arteries in nerves
A
True
13
Q
What happens to the nerve at places where it spilts
A
The nerve becomes stiff and may not slide well
14
Q
What does movement of the nervous system do (3)
A
- Prompts the flow of blood throughout the nerve
- Prompts removal of waste
- Stimulates axoplasmic flow in the axon
15
Q
What are the 2 types of axoplasmic flow in an axon
A
- Anterograde
2. Retrograde
16
Q
Do the capillaries in the nerves have smooth muscle
A
No
17
Q
What does the capillaries not having smooth muscle require
A
The nerve needs to be moved to pump blood throughout the nerves
18
Q
Are there lymphatics in nerves
A
No
19
Q
What does not having lymphatics in nerves make it hard to do
A
Get rid of swelling
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
21
Q
Where does nerve excursion first occur
A
The site immediately adjacent to the moving joint
22
Q
What is convergence
A
Nerve tissue is moving toward the joint causing motion
23
Q
What is divergence
A
Nerve tissue moving away from the joint causing motion
24
Q
When does convergence occur
A
When the nerve is tensioned at the joint moving
25
When does divergence occur
When the nerve is slackened at the joint moving
26
Going from wrist flexion to wrist extension what occurs to the median and ulnar nerves
They are both tensioned so convergence occurs
27
Going from elbow flexion to elbow extension what occurs to the median and ulnar nerves
Median nerve is tensioned so convergence occurs
| Ulnar nerve is slackened so diverengce occurs
28
True or False:
| Nerves try to move back to the resting position of the nerve
True
29
Are myelin and CT able to stretch and fold
Yes'm
30
True or False:
| Nerves are a lot of CT with small amounts of fascicles within them
True
31
Where is it apparent that nerves are full of CT and small amounts of fascicles
The cubital tunnel
32
What does tensile stress lead to in nerves
Elongation of the nerve (strain)
33
What occurs to the nerve in addition to the elongation
Transverse contraction in the center of the nerve occurs
34
What does the transverse contraction result in
Increased intraneural pressure
35
What does the amount of strain placed on the nerve depend on
Its relationship to the axis of rotation in the moving joint
36
Where does the most movement and strain occur during movement
At the joint moving
37
True or False:
| Sliders put limited to no strain on the nerve
True
38
True or False:
| Tensioners put more strain on the nerve
True
39
What does a steep slope on the stress strain curve indicate
That the tissue isn't very compliant
40
What amount of repetitive strain can nerves tolerate
6-8%
41
When do you start to see damage in a nerve due to the strain
11%
42
What can peripheral nerve injuries be classified as (2)
1. Mononeuropathy
| 2. Polyneuropathy
43
What is mononeuropathy
Single nerve issue
44
What is polyneuropathy
Multiple nerve problem
45
What are the 3 types of damage that occur to nerve
1. Traumatic myelinopathy
2. Traumatic axonopathy
3. Severance
46
What is the pathology of a traumatic myelinopathy
Demyelination
47
What is the pathology of a traumatic axonopathy
Axonal damage
48
What is the pathology of severance
Axonal damage and demyelination
49
What is the typical recovery of a traumatic myelinopathy
Complete and rapid recovery
50
What is the typical recovery of a traumatic axonopathy
Slow by regrowth of axons but good prognosis because Schwann cells are usually intact
51
What is the typical recovery of severance
Typically slow with incomplete recovery
52
True or False:
| Myelin is able to regenerate as long as the nucleus is still intact in the Schwann cell
True
53
What causes a traumatic axonopathy
Nerve on tension for a long period of time
54
In animal models what amount of prolonged lengthening lead to ischemia in the sciatic nerve
8%
55
In the animal model why was the reperfusion of the nerve potentially more damaging secondary to hyperemic blood flow
Because the amount of blood in the nerve is increased more than normal leading to increased pressure
56
What does the prolonged pressure from the increased fluid lead to
Damage to myelin because there are no lymphatics
57
What does acute compression of 20-30 mmHg interfere with in a nerve
Venous blood flow
58
What does acute compression of 35-50 mmHg cause
Reduced capillary flow
59
What does acute compression of 70 mmHg cause
Complete ischemia
60
What does chronic compression lead to in a nerve (4)
1. Epineural fibrosis
2. Demyelination
3. Axonal degradation
4. Perineural thickening
61
What does injury to peripheral nerves lead to
Wallerian degeneration
62
What is Wallerian degeneration
Everything distal to the injury dies and is broken down and taken up by the body
63
What happens to the proximal end of the damaged peripheral nerve
Upregulation of proteins from the cell body trying to recapture the lost end
64
When a nerve is severed what happens to the nerve endings
They retract away from the site of injury
65
When does Wallerian degeneration occur
When axons are injured
66
What does blockage of axonal transport do
Limits the flow of neurotrophic factors
67
What occurs due to the increased disruption of axonal transport
Axonal spheroids grow
68
What is an axonal spheroid
Build up of substances in an axon
69
What occurs once the axonal spheroid is formed
Wallerian degeneration leaving an end bulb on the proximal axon
70
Is the end bulb myelinated or not
Not myelinated
71
True or False:
| There is a large deposition of Na+ channels at the end bulb of damaged nerves
True
72
What does the large deposition of Na+ channels lead to
Spontaneous firing seen in people with chronic pain
73
Does the nerve need to be severed to have nerve death
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
True or False:
| Damage of a nerve can be due to constant use
True (carpal tunnel)
75
True or False:
| Na+ channels accumulate at end bulbs and areas of demyelination
True
76
What does the accumulation of Na+ channels in the regions of demyelination and end bulbs likely to occur due to
Abnormal trafficing
77
What does the accumulation of Na+ channels cause
Potential for ectopic discharge and pacemaker capability in neuropathic pain
78
What is ectopic discharge
When nerve stimulation occurs at a sight other than the normal site of stimulation
79
When does spontaneous ectopic firing in an injured nerve begin in myelinated axons
As early as 16 hours
80
When does spontaneous activity in unmyelinated axons that are damaged appear
Weeks following the initial injury
81
What fibers have spontaneous firing (2)
1. A-beta
| 2. A-delta
82
What is nociceptive pain
Pain due to stimulation of nociceptors largely dominated by C-fibers
83
What is neuropathic pain
Pain due to A-beta and A-delta fibers
84
When do C-fibers kick in during neuropathic pain
Much much later
85
True or False:
| Damage to axons leads to ectopic firing
True
86
What happens when we activate 2nd messengers for a long time
Adaption over time
87
True or False:
| Substance P is upregulated in large diameter dorsal root ganglion neurons following an axotomy
True
88
True or False:
| Phenotypic switching is likely the reason A-beta fibers contribute to neuropathic pain
True
89
Know chart about sequence of severed nerves
OKIE DOKIE
90
What are the negative signs and symptoms of peripheral nerve injury
Decreased nerve conduction velocity
91
Why is there decreased nerve conduction velocity
Demyelination occurs leading to no saltatory conduction
92
Get EMG slide cleared up by Dr. Brown
OK
93
What types of nerves have the ability to regenerate
Peripheral nerves
94
How long can a peripheral nerve take to heal
Several months
95
What needs to occur for axonal regeneration
Wallerian degeneration
96
Even though peripheral nerves can regenerate there is no guarantee the nerve will grow back completely
True
97
What does injury to the peripheral nerve do
Stimulate a number of signaling cascades that stimulate the upregulation of regeneration related genes
98
How much does a peripheral nerve grow a day
1 mm/day
99
True or False:
| Peripheral nerve injuries stimulate second messengers
True
100
What does the stimulation of second messengers stimulate
Transcription of proteins and other substances that influence nerve growth
101
True or False:
| Myelin growth is rapid
True
102
When does Wallerian degeneration occur in a completely severed nerve
3-5 days
103
What happens if a neuroma forms after injury
You will not get reconnection of the nerve
104
What do sliders increase
Axonal flow
105
What causes faster regrowth of nerves
Endurance training
106
True or False:
| Resistance training leads to slower regrowth of nerves
True
107
What do tensioners do
Allows us to elongate tissue potentially leading to realignment of tissues
108
True or False:
| The outcomes of resistance and endurance training eventually came out to be the same
True
109
Motivation
Good luck dude you are almost done for the summer!! Keep pushing and you will make it through!
