Central And Peripheral Nervous System Flashcards
When brain or spinal cord is damages why is there typically permanent injury
Injured axons fo not recover usually
Their proxima stumps begin to regenerate, sending sprouts into the area of the lesion. However this growth is blocked by astrocyte proliferation at the injury site and atonal sprouts are soon retracted
The posterior and anterior roots are the only sites where the motor and sensory fibers of a spinal nerve are segregated. What does this mean for surgery ?
Only at these locations can the surgeon selectively section either functional element for the relief of intractable pain or spastic paralysis (rhizotomy)
What is rhizotomy
Selectively destroy nerves roots in spinal cord
Do neurons proliferate in the adult nervous system ?
No
Except the olfactory epithelium
Are neurons destroyed replaced
Nope
When nerves are stretched, crushed, or severed, their axons degenerate mainly distal to the lesion because they depend on their nerve cell bodies for survival
Wooo
What happens if axons are damaged but cell bodies in tact
Regeneration and return of function may occur
What does pressure on the nerve cause
Best chance for recovery
Parenthesia-pins and needle sensation
Crushing nerve injury
Damages of kills axons distal to injury but nerve cell bodies usually survive and ct covering remain in tact
No surgery
Severed nerve
Regeneration less likely
Surgery -sutures through epineurium
Individual nerve bundles are realigned as accurately as possible
Anterograde(wallerian) degeneration
Degeneration of axons detached from heir cell bodies
Involves myelin sheath
What is the vasa nervosum
Small arteries supply peripheral nerves
Compression of vasa nervosum
Can cause nerve degeneration
What does prolonged ischemia of nerve cause
Damage no less severe than that produced by crushing of even cutting
Saturday night syndrome
Serious often permanent paresthesia
*can result from sustained use of tpurniquet during surgery
