3.7 PNS stuff Flashcards
myopathy
pathology in muscle
neuropathy
nerve is damaged
fascicular plexus
conjunction of fascicles
issues associated with myopathy
- muscle fiber degeneration
- motor unit problems: fiber isn’t getting input
What can be used to determine if it’s a myopathy or neuropathy?
EMG/NCV
What does EMG measure? What are the electrodes?
nerve activity
- stimulating electrode
- recording electrode
How is an EMG interpreted?
compare to established norms for nerve conduction speed
EMG below norm
neuropathy
EMG above norm
myopathy
purposes of botox injections
- cosmetic reasons
- migraines
- spasticity
- excessive sweating
How can botox help with migraines?
can be used to relax trigger points that may cause migraines
What do the issues addressed by botox have in common?
- NMJ with motor end plates
- EVERY muscle fiber has a motor end plate
How does botox work?
inhibits ACH release at NMJ
botulism toxin: bacteria
- anaerobic bacteria
- avoid bent cans that are puffy
What can happen with botulism infection?
systemic paralysis
mini endplate potential
- something that happens at the NMJ that helps support muscle health
- contributes to muscle tone
What happens at each spike on a mini endplate potential?
one packet of ACH is released
axonal regeneration speed
1-2 mm per day
axonal regeneration (CNS/PNS)
happens in the PNS, not the CNS
severance neuropathy
axon is severed
severance neuropathy: proximal stump
- axonal sprouts grow out toward the distal stump
- intact cell body
What must be the case for regeneration to occur?
the cell body MUST be intact
What happens when there’s a nerve injury?
get immune cell recruitment to clear debris left over
What special chemicals do Schwann cells secrete?
- chaemotactic factors
- neurotrophic factors
chaemotactic factors
promotes growth and helps axon guidance to the correct distal stump
neurotrophic factors
growth factors in neurons
Why is the CNS not permissive to regeneration?
- no growth factors secreted by glia
- chemotactic factors help with NEW neuronal growth, not regeneration
injury to CNS
- glial cells push end feet into the injury and creates a scar (glial scar)
- axons cannot grow through a glial scar
