nerve injury

Question 1

Neurotmesis

Answer 1

severed trauma knife, glass

severance of entire nerve ending
wallerainn degneration occurs

surgery required

Question 2

Axonotmesis

Answer 2

loss of sxon and myelin cointunity.
wallerian degenration occurs
object traums, acute crushing forces

Question 3

Neurapraxia

Answer 3

wallerian doesnt occur

neural tissue still in tact

compression of mylein sheath

Question 4

sensory receptors how long can be maintained?

Answer 4

2- 3 years

Question 5

How long do motor fibres last

Answer 5

up to 3 weeks

Question 6

Limits to regeneation

Answer 6

scar tissue

if schawnn cell tube is not re-populated by the axon within 4 months it will close
More distal the better chance the regenerating

Motor fibres will atrophy after 3 weeks after injury. end plates can be maintained for 1 year

sensory up to 2-3 years

Question 7

Regeneration (several months)

Answer 7

Schawnn cells form tube for growth and produce neurtrophic factors
(neural growth factors)

Axonal buds grow down the tube and reconnect with muscle and sensory tissues (1-1.5mm per day)

Question 8

Wallerian Degenration meaning

Answer 8

biochemical changes that occur in axons and Schwann cells distal to the site of inury

first 3-5 days injury