Diagnostic Procedures Flashcards
fastest motor nerve fiber type
A alpha (skeletal mm)
slowest motor nerve fiber type
C (post ganglionic ANS)
3 layers of nerve
Epineurium (outer most layer that is thicker in areas of higher stress)
Perineurium (surrounds bundles of axons is peripheral nerves)
Endoneurium(around each and every axon (nerve fiber) of every peripheral nerve
AP conduction in unmyelinated nerves
eddy currents
AP conduction in myelinated nerves
saltatory conduction (nodes of Ranvier)
Neuropraxia/1st degree
segmental demyelination; axon remains intact, but no AP can be conducted at demyelinated region
Axonotmesis/2nd degree
Axonal and myelin degeneration distal to site; 3 CT coverings intact
Axonotmesis/3rd degree
Axonal and myelin degeneration distal to ite; endoneurium no longer intact
Axonotmesis/4th degree
Axonal and myelin degeneration distal to site; endoneurium and perineurium no longer intact
Neurotmesis/5th degree
Axonal and myelin degeneration distal to site; no CT coverings intact at site of lesion
axonal regeneration rate
1 in/month
remyelination rate
proximal to distal (matures at 1 year) and has a slower conduction velocity (more nodes of ranvier)
4 periods of axonal regeneration
initial delay
site delay
axonal regrowth
functional recovery
cell body recovery from chromatolysis
initial delay
axons traversing damaged zone
site delay
growth cone
axonal regrowth
sufficient numbers and combination for fxn
functional recovery
chromatolysis
cell body response proximal to injury site - soma swells, nucleus moves to periphery
