Topic 16 - PNS Injuries 1

Question 1

The myeline sheath in peripheral nerves consists of _______ _____ wrapped around individual axon fibres.

Answer 1

Schwann Cells

Question 2

The outermost membrane of an individual nerve fibre in the PNS.

Answer 2

Neurolemma

Question 3

Gaps between the Schwann cells.

Answer 3

Nodes of Ranvier

Question 4

When impulses travel faster along myelinated fibres than along unmyelinated ones.

Answer 4

Saltatory Conduction

Question 5

What are the 3 additional connective tissue layers that axons are covered by?

Answer 5

1) Endoneurium
2) Perineurium
3) Epineurium

Question 6

A connective tissue layer surrounding individual axons.

Answer 6

Endoneurium

Question 7

A connective tissue layer surrounding bundles of axons.

Answer 7

Perineurium

Question 8

A connective tissue layer surrounding the entire peripheral nerve.

Answer 8

Epineurium

Question 9

T/F - Peripheral nerves carry predominately afferent information and not efferent information.

Answer 9

False - Peripheral nerves carry predominately BOTH afferent and efferent information.

Question 10

________ refers to sensory or proprioceptive information and ________ refers to motor information.

Answer 10

Afferent
Efferent

Question 11

Some peripheral nerves carry _________ fibres, such as the ___________ outflow from T1-L2 and the _______________ outflow from S2-S4.

Answer 11

Autonomic
Sympathetic
Parasympathetic

Question 12

Common causes of peripheral nervous system ________ damage include:
- Direct trauma
- Infection
- Compression
- Injury repair complications
- Poison/toxins
- Diseases causing peripheral neuropathies
- Birth trauma
- Loss of blood supply
- Extremes of temperature/radiation

Answer 12

Neuronal

Question 13

T/F - The most common cause of PNS neuronal damage is compression.

Answer 13

False - The most common cause of PNS neuronal damage is DIRECT TRAUMA.

Question 14

A common cause of PNS neuronal damage resulting from:
- Severance or crush injuries (e.g. MVAs, industrial accidents)
- Traction injuries (e.g. stinger/burner)
- Forcible overextension of a joint or repeated small traumas

Answer 14

Direct Trauma

Question 15

A common cause of PNS neuronal damage due to the presence of a pathogen (e.g. infective neuritis).

Answer 15

Infection

Question 16

A common cause of PNS neuronal damage resulting from:
- Improper immobilization
- Poorly fitted crutches
- Prolonged cane/walking frame/wheelchair use or inadequate padding
- Carpal tunnel syndrome, TOS, compartment syndromes, meralgia paresthetica, tumors & prolonged postures
- Prolonged pressure at bony prominences (e.g. sleep, intoxication, bicycle riding)

Answer 16

Compression

Question 17

A common cause of PNS neuronal damage resulting from:
- Nerve is tractioned or compressed by bony calluses (e.g. dinner fork deformity d/t Colles fracture)
- Nerve is caught up in restrictive scar tissue
- Nerve is entrapped in a damaged joint or bone (e.g. shoulder dislocation)
- Iatrogenic inflammation

Answer 17

Injury Repair Complications

Question 18

A common cause of PNS neuronal damage resulting from:
- Alcoholism
- Occupational contact with chemicals/abuse of chemicals

Answer 18

Poisons/Toxins

Question 19

A common cause of PNS neuronal damage resulting from:
- Diabetes
- AIDS
- Poliomyelitis
- Hansen’s Disease (aka. Leprosy)

Answer 19

Diseases Causing Peripheral Neuropathies

Question 20

A common cause of PNS neuronal damage resulting from:
- Erb’s palsy
- Klumpke’s palsy

Answer 20

Birth Trauma

Question 21

A common cause of PNS neuronal damage resulting from:
- Extreme edema
- Frostbite

Answer 21

Loss of Blood Supply

Question 22

T/F - A common cause of PNS neuronal damage is from radiation or extremes in temperature, especially hot.

Answer 22

False - A common cause of PNS neuronal damage is from radiation or extremes in temperature, especially COLD.

Question 23

The process that occurs when an axon/nerve fibre is cut, severely tractioned to the point of separation, or crushed. It can also occur when axons sustain severe and prolonged compression.

Answer 23

Wallerian Degeneration (aka. Anterograde Degeneration)