Pathophysiology of nervous system

Question 1

Difference between saltatory and continuous propagation ?

Answer 1

continuous = unmyelinated fibers, takes a long time
saltatory = myelinated fibers, signal conduction is a lot faster

Question 2

nerve conduction studies : difference in amplitude and delayed response

Answer 2

1) difference in amplitude = conduction block from damage to nerve fibers (axonal damage)
2) delayed signal = demyelination (damage to myelin) -> conduction velocity is reduced (caused by nerve compression for example)

Question 3

What is a motor unit ? Difference between face and legs ?

Answer 3

one nerve cell and all the muscle fibers it innervates.
In face -> not many fibers per cell -> precise expressions and movements

Question 4

What happens when we cut a nerve completely or only partially ?

Answer 4

1) completely : distal part of nerve is destroyed, it can regrow but takes years
2) collateral reinnervation, within 2-3 weeks (thin myelin sheet -> unstable signal)

Question 5

difference between carpal and cubital tunnel syndrome

Answer 5

1) carpal : median nerve that goes into the wrist is compressed
2) cubital : ulnar nerve at the elbow is compressed