Peripheral nerve anatomy

Peripheral nerves relay information from the central nervous system to the periphery. Their anatomical structure can be considered in terms of the constituent parts:

• neurones
• glial cells
• connective tissue
• blood supply

Groups of neurones organise together as a fascicle. The way fascicles arrange in nerves is predictable according to the distance from the spinal cord:

• monofascicular nerves:
  • have one fascicle alone
  • can be either pure motor or sensory
  • examples include the terminal branches of digital vessels
• oligofascicular:
  • several fascicles within nerve
  • again, usually purely motor or sensory but occasionally of mixed function
  • eg common digital nerves
• polyfascicular:
  • major nerves containing fascicles with different functions eg sensory and motor
  • eg ulnar nerve
  • extensively mapped for the larger nerves in cadaveric studies:
    • detail the position of groups of motor fascicles in relation to sensory fascicles
    • help in approximating the correct fascicles for function when nerves are repaired