P2 PHYSIOLOGY Flashcards
nerve injury Regeneration of nerves
Mention the 2 causes of nerve injury
1- trauma
2- metabolic / toxic
examples of metabolic or toxic causes of nerve injury
- DM
- renal failure
Individual nerve fiber surrounded by
endoneurium
Each fascicle of nerve fibers is surrounded by
perineurium
The outermost layer of dense, irregular connective tissue surrounding a peripheral nerve
Epineurium
grading systems of nerve injury
1- seddon
2- sunderland
seddon grading system depend on
1-nerve components affected
2- loss of functionality
3- ability to recover spontaneously
rupture of nerve & its no longer a continuous fiber is known as
neurotmesis
wallerian degeneration is seen in which classification / stage
axonotmesis grade2
an active process of anterograde degeneration of the distal end of an axon that is a result of a nerve lesion or injury.
Wallerian degeneration
Recovery of grade 1 nerve injury is within
within 1 6 week period
paralysis of the extensor muscles of the wrist and fingers due to compression of the radial nerve where it passes in the groove around the humerus of the upper arm is known as
Saturday night Palsy
what grade of nerve injury in which the Injury not only to myelin sheath but also to the axon itself & is Common in crush injuries and displaced bone fractures.
grade 2 / axonotmesis
what grade of nerve injury in which the to myelin sheaths, axon, and endoneurium, with sparing of the perineurium and epineurium. with some scar tissue
grade 3
what grade of nerve injury in which the Injury to all nerve trunk elements except the epineurium (Partial transection). with Dense scar tissue.
grade 4
what grade of nerve injury is Complete transection of all neural and connective tissue elements of the nerve trunk.
grade 5 / neurotmesis
poor prognosis is seen if the injury site is
close to the neuronal cell body
good prognosis is seen if the injury site is
close to the target site
Repair mechanisms in traumatic nerve injury
- segmental demyelination
- degenerative process
Repair mechanisms in metabolic / toxic nerve injury
axonal degeneration
Myelination in periphery is done by
schwann cells
Represents a switch in function of cell body from axon maintenance to axon regeneration.
chromatolysis
partial nerve injury recovery time
3-6 months
Successful Axon Regeneration depends on
1- proper environment
2- endoneurial tube condition
3- presence of viable end organ
in axon regeneration in CNS
dense scar tissue is a result of
astrocytes
proteins expressed by oligodendrocytes as components of CNS myelin
myelin associated inhibitors
main inhibitory molecules found in astroglial scar
Chondroitin Sulfate Proteoglycans
cells in CNS that are responsible for myelination
Oligodendrocytes
Procedure in which a small piece of donor nerve is used to bridge the gap between the two nerve ends
nerve graft
Transfer of functioning
nerves that are close to the target to the injured nerve is a procedure known as
nerve transfer
Sewing the two ends of a nerve together , if nerve has been cut a procedure known as
nerve repair
Removal of scar from the nerves to prevent scar tissue from blocking the
nerve from regenerating is a procedure known as
neurolysis