Peripheral Nerve Injury

Question 1

Axonal response to injury

Answer 1

Wallerian degeneration

Question 2

Wallerian degeneration aka

Answer 2

anterograde degeneration

Question 3

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

Answer 3

Wallerian degeneration

Question 4

Wallerian degeneration occurs in stages:

Answer 4

1. Degeneration
2. Clearance
3. Regeneration
4. Growth and re-myelination of new axons

Question 5

T/F Degeneration is when injury causes the Proximal part of the axon to become separated from its cell body.

Answer 5

Fasle
Distal

Question 6

T/F In Degeneration, the injured axon(s) that is no longer connected to its cell body degenerates proximally from the injury site all of the way along its pathway

Answer 6

False Distally

Question 7

It also degenerates for a short distance proximally from the injury site to the nearest node of _________ .

Answer 7

Ranvier

Question 8

Axonal degeneration is followed by degradation of the myelin sheath and neurolemma: infiltration by macrophages, mast cells and Schwann cells clear fragmented axonal material and debris from the injury site and along the pathway of the axon.

Answer 8

2. Clearance

Question 9

During Clearance, the axon, myelin sheath and neurolemma of each injured axon have now _________ from the site of the injury along the pathway of the nerve.

Answer 9

Degenerated

Question 10

During Clearance, all that remains distal to the injury site is the nerve stroma, i.e. the epineurium, perineurium and __________ sheath. Exceptions include crush injuries and any other injuries that destroy ______ nerve stroma)

Answer 10

Endoneurial
Distal

Question 11

During Clearance, The endoneurial sheath distal to the injury remains as a hollow tube and is ________ for regeneration

Answer 11

ESSENTIAL

Question 12

During Regeneration, these cells rapidly reproduce and migrate from nearby neurons and via the blood
stream towards the injured nerve?

Answer 12

Schwann Cells

Question 13

During Regeneration, the______ ______ shifts its function from synaptic transmission to cellular ______. Axoplasmic material, nutrients and building blocks are moved from the cell body along the ______ intact part of the axon towards the injury site.

Answer 13

cell body
repair
proximal

Question 14

During Regeneration, _________ sprouting: the proximal end of the axon sends out neuronal sprouts which advance towards the intact _________ tubes distal to the injury site

Answer 14

Neuronal
Endoneurial

Question 15

During Regeneration, the axonal sprouts begin bridging the gap between the _______ and _______ connective tissue segments while the cell body continues to send building blocks along the ______ towards the regenerating axon.

Answer 15

Proximal and Distal
Axon

Question 16

______ _______ is the initial healing phase lasts on average 10 – 12 days

Answer 16

Gap Repair

Question 17

Gap repair lasts how long on average?

Answer 17

10-12 days

Question 18

Gap repairs includes how many steps? Name them?
Name the other aspects within gap repair?

Answer 18

3
Initial injury
Degeneration
Clearance
Cell body production of new axoplasmic material
Neuronal sprouting from proximal stump of injured axon towards the distal endoneurial tubes.

Question 19

what is the initial healing time?

Answer 19

is the time it takes for the degenerated axon to bridge the gap between the proximal and distal segments of the injured nerve and reach the distal endoneurial tubes.

Question 20

During Growth and re-myelination of new axons, If the neuronal sprout reaches the distal endoneurial tube, it grows into it and advances along the _______ _________, gradually reaching and re-innervating its target tissues.

Answer 20

nerve pathway

Question 21

During Growth and re-myelination of new axons, as the newly constructed axon moves along the _______ tube, Schwann cells ____-________ the axon.

Answer 21

Endoneurial
Re- myelinate

Question 22

In summary, the only way a particular axon can become functional again is through growth of the _________ part of the axon into the correct _________ tube and along its original route

Answer 22

Proximal
Endoneurial

Question 23

T/F Regeneration on average is said to occur at a rate of 1 mm per day

Answer 23

True