Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

ANAT2012 > Neuroanatomy L5: Peripheral nerve biomechanics > Flashcards

Neuroanatomy L5: Peripheral nerve biomechanics Flashcards

1
Q

Axonal transport relies on _______.

A

O2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Neurons have ____ (small/large) body (soma) and axons ha _____ lengths.

A

large; varying

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is a soma?

A

contains organelles required for cell to maintain itself

(makes macromolecules, neurotransmitter- need)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the glial cells of the PNS called?

A

schwaan cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the glial cells of the CNS called?

A

olidendrocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is anterograde transport?

A

cell body to axonal terminal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is retrograde transport?

A

from axonal terminal to cell body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Is anterograde transport fast or slow?

A

Fast

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How does axonal swelling occur?

A

if there is obstruction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What occurs in axonal swelling?

A

disconnect proximal from distal.

This means distal stump will degenerate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

An axon is _____ (high/low) maintenance- ______ (must/does need to be) supported

A

high; must

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What type of connective tissue is endoneurium?

A

Loose connective tissue proper

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Is endoneurium around every axon?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is perineurium?

A

Lamellated sheath enclosing funiculi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the function of perineurium?

A

Bundle axons together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What type of connective tissue is perineurium?

A

dense irregular CTP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are 3 things that perineurium consists of? Why?

A
  1. Type I collagen
  2. Type II collagen
  3. elastic fibres

circular, oblique and longitudinal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are 2 types of connective tissue in epineurium?

A
  1. interfascicular areolar connective tissue
  2. outer external sheath (DICTP)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the function of epineurium?

A

between adjacent fascicles or funiculi (same)- “packing”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the function of interfascicular areolar connective tissue in epinerium?

A

fill in space

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the function of outer external sheath (DICTP) in epinerium?

A

outer limit of a peripheral nerve- including axon (more formed)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the function of the mesoneurium?

A

between nerve and muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What type of tissue is mesoneurium?

A

loose areolar CTP surrounding nerve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

List 2 functions of why some nerve structures made of dense connective tissue proper.

A
  1. restricts unwanted movement
  2. provides restriction of forces or movement
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

List 2 functions of why some nerve structures made of loose connective tissue proper.

A
  1. allow movement between structures
  2. has spaces for pathway for blood vessels

(small nerve innervate larger nerve)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

The structure of a nerve is constantly changing along its ______. This means that they are always _______ with the whole length of the nerve in a ______ fashion (i.e, when you section a nerve you will always find _____ (different/same) number of fascicles)

CHECK

A

length; interweaved; uniform; different

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

The size and number of fascicles are _____ (directly proportional/inversely proportional) to each other.

A

Inversely proportional

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Less number of fascicles means that they are _____ (larger/smaller) in size

A

larger

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

More number of fascicles means that they are _____ (larger/smaller) in size

A

smaller

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

There are ____ (more/less) fascicles which are _____ (large/small) in size where a nerve crosses a joint? Why?

A

More; smaller

provides more flexibility (similar to collagen) but still have strength (related to CSA)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

A nerve ________ (needs/does need) a good blood supply. Why?

A

needs

relative tortuosity of the blood vessels accommodates strains and gliding of the nerve during motion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is the function of the vascular plexus in epineurium?

A

to support (wouldn’t only want one-) want multiple

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is the vascular system in endoneurium like?

A

longitudinal interconnected vessels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What is the extrinsic vessel in mesoneurium like? What is their function? List 2.

A

longitudinal vessels that are interconnected

  1. Acts as as a safety/back up if one of them is occluded
  2. Supplies nutrients
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

How can nerves be a source of pain?

A

They are innervated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What are the 2 purposes of physios knowing nerve loading techniques (i.e nerve flossing)?

A
  1. advice patients to avoid specific positions
  2. give exercise to move/make sure nerve keeps gliding
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

When do nerve injuries occur?

A

When the load imparted to the nervous system exceeds its tolerance to mechanical forces, then injury can occur

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What are the 4 factors that the type of pathology and extent of injury depends on?

A
  1. TYPE of loading (tension, compression, shear)
  2. AMOUNT of load (or deformation)
  3. RATE of which the tissue is load (slow or rapid- viscoelastic- strain rate)
  4. DURATION: acute (severing or rapid stress= rupture) VS repetitive (overload –> ultimate stress limit will decrease) or chronic (pathologically affected by chronic compression to tension)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

The capacity of the NS to regenerate depends on ____the injury occurs, the ____ nervous system having greater capacity to heal and regenerate than the _____ nervous system.

A

where; PNS; CNS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What happens first in a nerve: elongation or tension.

A

Elongation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

The length of a nerve & its axons between 2 points on a limb is ____ (longer/shorter) than a straight line.

A

longer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What is “undulating” a nerve?

A
  • waving (has some level of slack/toe-in region)
  • in-built levels/areas of slack before structures of peripheral nerve undergo tension
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

What are 3 characteristics of “undulating” a nerve?

A
  1. nerve in its bed
  2. fascicles within nerve
  3. axons within fascicles
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

What happens in “initial elongation” of a nerve?

A

the nerve and the fascicles straighten –> perineurium 1st to resist load

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

What happens in “increasing elongation” of a nerve?

A

nerve fibres straighten –> perineurium (doesn’t fail can continue to stress), endoneurium, myelin sheath &axon resist lengthening

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

What is something special to note about perineurium?

A
  • first to resist load (dense connective tissue proper)
  • main component of nerve that resists tension perineurium can continue to strain (doesn’t fail) but slowly other structures start to undergo stress/strain
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

What is excursion?

A

Displacement or gliding of a nerve relative to the surrounding nerve bed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

Displacement or gliding of a nerve relative to the surrounding nerve bed is called _______.

A

excursion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

The ______ and ______ (which way and how much it moves) of nerve excursion are dependent upon the anatomical relationship between the ___ and the _______ in the moving joint. Give an example using the median and radial nerve with elbow flexion/extension.

A

direction; magnitude; nerve; axis of rotation

eg. elbow - flex/ext median (anteriorly to ebow jt)- tensioned in extension radial (posteriorly to elbow jt) - stack in extension

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

With elongation of the nerve bed, the nerve glides ____ (towards/away from) the moving joint. Give an example of a test for hip flexion.

A

toward

eg, single leg raise (knee, ankle and lumbar spine in neutral (extension) while lying on bed.

WIll test hip flexion) tibia and common fibula - towards hip lumboscaral - towards hip

51
Q

Nerve excursion occurs _____ (first/last) in the nerve segment immediately adjacent to the moving joint. As limb movement continues, excursion occurs at nerve segments that are progressively more _____ (proximal/distal) from the moving joint. Give an example using the tibial nerve in the thigh and the leg.

A

first; distal

Eg. tibial nerve in thigh will move first compared with the one in the leg

52
Q

The magnitude of excursion is ______(greatest/least) in the nerve segments adjacent to the moving joint and is ______(greatest/least) in the nerve segments distant from the joint.

A

greatest; least

53
Q

When moving from 90 degrees elbow flexion to 0 degrees, what happens to the median nerve?

A

Median nerve in arm and forearm both move towards elbow (converge towards joint medial nerve)

54
Q

When moving from 90 degrees elbow flexion to 0 degrees, what happens to the ulnar nerve?

A

Ulnar N glides away from elbow

55
Q

When moving from wrist extension from 0° to 60° extension, what happens to the median and ulnar nerve?

A

both medial and ulnar nerve beds lengthen –> both nerves glides towards the wrist (because they are both anterior when in the wrist area)

56
Q

Where is the most movement of nerve when moving the wrist (movement occurs closest to the joint) when comparing the forearm and arm.

A

In forearm

57
Q

What is the elastic limit (%)for a typical tensile load-deformation diagram for a peripheral nerve (slow loading rate) in regards to typical stress/strain values?

A

8-20% strain

58
Q

What is the ultimate failure (%) for a typical tensile load-deformation diagram for a peripheral nerve (slow loading rate) in regards to typical stress/strain values?

A

30% strain

59
Q

Why is there an increase number in funiculi for a typical tensile load-deformation diagram for excised human peripheral nerve (slow loading rate) compared to typical stress/strain values?

A

if more funiculi = more perineurium = stronger = can withstand more stress

60
Q

Why is it important to know the rate of loading?

A

Different nerve behaviour based on loading rate

61
Q

Are spinal nerve roots stronger or weaker? Why? What does that mean?

A

Weaker perineurium absent

Failure at lower stress or strain

62
Q

Modulus of elasticity varies along length of nerve. Where is it lowest? Why?

A

closest to the joint- doesn’t resist

63
Q

What occurs before the elastic limit of a nerve?

A

Physiological failure occurs before elastic limit

64
Q

What does the stress-relaxation curves show when nerves are being tensioned?

A
  • If strain a peripheral nerve - still undergoes stress relaxation, especially in in first 20mins and still level off
  • Still after 1 hr still (a lot of) 60% of original tension remains in the nerve
65
Q

What do the peak nerve conduction velocity show when nerves are being tensioned? (group A at 8.9% and group B at 16.1%). Be specific with group A and B.

A

Group A: can return to function (Function of group A wasn’t decreased due to the strain)

Group B: can’t return to normal function. Function of group B was decrease due to the strain –> impairment of function. Significant deficit in nerve conduction velocity (function of axons). Past the elastic limit, Damage to structures with the nerve. This means the elastic limit (where axonal damage/ axons had impaired function occurs is >8.8% and definitely at 16%

66
Q

What do the nerve blood flow show when nerves are being tensioned? (group A at 8.9% and group B at 16.1%). Once the traction has been removed, what happens to group A and B.

A

When traction a nerve, will decrease blood flow but there was no significant difference between Group A and B.

Decrease blood flow is not the only reasoning for decrease in nerve conduction

Group A: recovered

Group B: did not recover

67
Q

When a nerve is lengthened, what happens to the diameter? Where does narrowing occur most?

A

decrease diameter

narrowing occurs in the middle

68
Q

How does lengthening a nerve (decreasing diameter) affect the nerve? List 2 effects.

A
  1. increases intra-axonal pressure and this affects axonal transport mechanism
  2. Impaired blood flow (increase pressure inside nerve- blood needs pressure gradient- if increase inside higher than venous - no blood flow
69
Q

What is the the theory of nerve pathology in regards to tension and compression?

A

if subject a nerve to more tension/compression (chronic or acute) will impede blood flow and axonal transport mechanism

70
Q

A nerve retains its elastic properties until the ____ fails but usually the rupture of axons _____ rupture of the perineurium

A

perineurium; precedes

71
Q

Nerve –> ______ –> axon

A

fascicle

72
Q

Axons (can only withstand 4% before fail) - usually fail before the _____. What does that mean for the nerve?

A

perineurium

Can have a nerve that looks intact but the axons and as a result the function is impaired

73
Q

The relative amounts of _______ and ______ tissue varies within a nerve,

A

fascicular; epineurial

74
Q

What is epineural tissue?

A

minimize compression on tissue inter-fascicular- bulk packing

75
Q

In general, fascicular contribution to ______% to ____ %cross-sectional area

A

30-70%

76
Q

Forces are imposed on the _____ component of the nerve

A

main

77
Q

What is the function of increased epineural tissue?

A

Increase epineurial tissue acts a s a shock absorber - more epineurial tissue in area that need more shock absorption or protection

78
Q

Chronic loading of neural tissue can also result in_______. What type of force is this often due to? Give 2 examples of these forces of anatomical structures.

A

neural damage often due to compression of the neural tissue

  1. e.g. compression of spinal nerve roots in degenerative spinal disorders
  2. e.g. compression loading of the median nerve in the wrist in carpal tunnel syndrome
79
Q

The likely that the injury mechanism for nerve damage is a mixture of _______ and ______due to a compromised blood supply to the tissue.

A

mechanical compression; ischemia

80
Q

What is the function of the axonal transport system?

A

decrease congestion and pressure inside axon

81
Q

What is the pathophysiology associated with the development of musculoskeletal peripheral neuropathic pain?

A
82
Q

What are the 8 factors that increase pressure in the confines space (in perineurium), which causes impairment of impulse conduction related to amount of intraneural oedema & myelin changes?

A
  1. Inflammatory response
  2. Immune cell activation
  3. Intraneural oedema
  4. Further of venous congestion
  5. Further impairment of axoplasmic flow
  6. Fibroblast proliferation & fibrosis
  7. Progressive demyelination
  8. Axonal degeneration
83
Q

What is neurodynamics?

A

Nerve elongation & nerve excursion techniques

84
Q

What is the purpose of neurodynamics?

A

a dynamic variation in intraneural pressure when correctly applied may facilitate evacuation of intraneural oedema and reduce symptoms

85
Q

What is the benefit of nerve gliding exercises?

A

nerve gliding exercises may also limit fibroblastic activity and minimise scar formation via normal and early use of mesoneurial gliding tissues

86
Q

What are 2 systemic factors which increase predisposition to a nerve pathology?

A
  1. Diabetes
    • increase collagen
    • increase CSA
    • (compromised more easily when goes through tunnel (esp. tarsal tunnel))
  2. Thyroid disease
87
Q

What are 5 non-systemic factors which increase predisposition to a nerve pathology?

A

presence of a nerve disorder is a predisposition for the development of a secondary nerve disorder in the same quadrant “double crush phenomena”

  1. Axonal transport
  2. Altered ion channels
  3. Neuroinflammation
  4. Central sensitisation
  5. Altered neural biomechanics
88
Q

What are the 5 types of Seddon’s and Sunderland’s classification systems of the pathoanatomy of nerve injury?

A
89
Q

What is type 1 nerve injury?

A

Neuropraxia

Temporary conduction block (shock- usually recovers within 1-3 weeks - no physical disruption)

90
Q

What is type 2 nerve injury?

A

Axonotmesis

  • severing axons fail first (ruptured) but connective tissue tunnels are still intact (
  • endoneurial tube, perineurium and epineurium intact
91
Q

What is type 3 nerve injury?

A

Axonotmesis + endoneurial tube destroyed

  • (perineurium and epineurium intact)
92
Q

What is type 4 nerve injury?

A
  1. Axonotmesis + endoneurial tube & fascicle destroyed
  2. Fibrosis
  • (epineurium intact)
  • sensory and motor nerves intermingling- not going to target
93
Q

What is type 5 nerve injury?

A

Neurotmesis

  • Complete transection of nerve
94
Q

If connective tissue is still intact during nerve injury, axon can ____ and is guided by _______ to reach correct/target organ

A

sprout; intact tunnel

95
Q

While there are 5 types of nerve injuries, clinically, utility- most peripheral nerve injuries are _____.

A

mixed

96
Q

Following axonal transection (severed and interrupted axonal transport), whole neuron goes into a different way of functioning- looks different as well. What are 5 changes?

A
  1. Cell body swells, nucleus moves peripherally = change in metabolic priority from production of neurotransmitters to production of structural materials needed for axon repair and growth
  2. Degeneration of proximal axon (swelling in distal part of proximal stump)
  3. Wallerian degeneration (distal stump) starts within 2-4 days of injury
  4. Schwann cells detach from axons, proliferate & clear cellular & myelin debris (become like macrophages)
  5. Schwann cells align longitudinally & express stimulating factors to direct nerve regrowth toward target organ. (form new tunnel to guide to target organ)
97
Q

Following axonal transection (severed and interrupted axonal transport), the cell body ____ (swells/shrinks), nucleus moves ______ (axially/peripherally). This means there is a change in______ priority from production of neurotransmitters to production of structural materials needed for axon ____ and ___.

A

swells; peripherally; metabolic; repair; growth

98
Q

Following axonal transection (severed and interrupted axonal transport), there is degeneration of the ________ (proximal/distal) axon (swelling in ___ (proximal/distal) part of proximal stump)

A

proximal; distal

99
Q

Following axonal transection (severed and interrupted axonal transport), ______ degeneration (distal stump) starts within 2-4 days of injury

A

Wallerian

100
Q

Following axonal transection (severed and interrupted axonal transport), schwann cells detach from ______, proliferate & clear cellular & myelin _____ (become like ______)

A

axons; debris; macrophages

101
Q

Following axonal transection (severed and interrupted axonal transport), schwann cells align ____ & express stimulating factors to direct nerve regrowth toward target organ. (form new ___ to guide to target organ)

A

longitudinally; tunnel

102
Q

What is the primary repair of nerve transections called?

A

neurorrhaphy

103
Q

What are the 2 types of primary repair of nerve transection?

A
  1. Epineurial repair
  2. Fascicular repair
104
Q

What is Epineurial repair?

A

bring the outer external sheath together

105
Q

What is Fascicular repair?

A

grab perineurium and attach together

106
Q

When is nerve grafting used?

A

when primary repair cannot be performed without undue tension.

  • if the segments are too far away (distance is too far- and tension)- nerves can’t withstand tension
107
Q

What is Autografting?

A

take another sensory cutaneous nerve and interpose it

108
Q

What are the 4 types of autografts?

A
  1. sural N
  2. medial antebrachial cut
  3. lateral fem cutaneous
  4. superficial radial N
109
Q

What is the rehab process for an autograft? When can full function be returned?

A

graft repair site & graft itself regain the same tensile strength as the native nerve by 4 wks (limb immobilised during this period to protect the graft)

110
Q

What is allografting?

A

from animals

111
Q

What are synthetic tubes used for?

A

guide regrowth

112
Q

What are the 3 types of nerve grafting?

A
  1. Autografts
  2. Allografts
  3. Synthetic tubes
113
Q

What are the 3 preoperative goals in a denervated extremity?

A
  1. Protection & maintainenance of range of motion
  2. Bandaging, splinting, ROM exercises to prevent contractures & deformity, support joints, limit oedema, maintain blood and lymphatic flow and prevent tendon adherence.
  3. Direct muscle stimulation to reduce muscle atrophy / psychological benefit
114
Q

What are the 3 postoperative goals in a denervated extremity?

A
  1. Early-phase sensory re-education decreases mislocalisation and hypersensitivity and reorganises tactile submodalities, such as pressure and vibration.
  2. Hydrotherapy can be helpful to improve joint contractures and eliminate the effects of gravity during initial motor recovery, thereby enhancing muscular performance.
  3. Biofeedback may provide sensory input to facilitate motor reeducation.
115
Q

What is the main pre-operative goals in a denervated extremity?

A

decrease stress on areas and support joint, muscles, tissues around injury

116
Q

What is the main post-operative goals in a denervated extremity?

A

stimulate and re-direct the nerve regrowth towards correct organ (biofeedback electrical stimulation can stimulate nerve growth and sensory and motor repair and maintain muscles with electrical stimulation, hydrotherapy etc)

117
Q

Electrical stimulation ______ (increases/decreases) sensory & motor neuron regeneration

A

increases

118
Q

Based on an experiment, re-innervation of thenar muscles post carpal tunnel release happened in half the time when using ________ compared to the controlled healing

A

electrical stimulation

119
Q

What is Tinel’s sign?

A

A positive tingling sign in response to mechanical stimulation indicates that some regeneration is occurring

120
Q

How to test for Tinel’s sign?

A

mechanosensitive- tap

postive sign- tingling

121
Q

The most important clinical information is ____________ of the sign seen with frequent evaluation of the patient. How is this information found?

A

progression able to monitor the progression and know where the nerve travels

122
Q

What does a positive Tinel’s sign that is progressing signify?

A

Regenerating nerves are able to pass the lesion

123
Q

What does a positive Tinel’s sign that is static at the site of the injury signify?

A

site of injury indicates the presence of a neuroma (forming a clump) and the need for exploration

124
Q

In cases of nerve lesions with large anatomical gaps that had a positive tingling sign, a Tinel sign could not be elicited ______ (proximal/distal) to the site of injury.

A

distal

ANAT2012 (31 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions