1st degree nerve injury
Neuropraxia
Focal damage of myelin fibers around axon
Connective tissue sheath remains intact
2nd degree nerve injury
Some disruption/injury to the axon itself
Myelin sheath remains intact
3rd degree nerve injury
Disruption of axon and endoneurium
4th degree nerve injury
Disruption of axon, endoneurium, and perineurium
5th degree nerve injury
Disruption of axon, endoneurium, perineurium, and epineurium