• The central nervous system – Brain, Spinal cord
• The peripheral nervous system - All the nerves except for the brain and the

spinal cord. It contains 3 branches:

• Sensory
• Motor
• Autonomic

Neuropathy is a disorder of the peripheral nervous system
SFN is a form of neuropathy that affects the smaller fibers in the peripheral nervous system. The damage can include sensory and autonomic nerve fibers.

The skin biopsy tests the small fibers, and EMG tests the large fibers of the peripheral nervous system.