Peripheral nerve injuries are one of three types: neuropraxia, axonotmesis and neurotmesis. Blunt trauma and traction injuries may cause nerve transection when associated with open fractures, but the majority result in neuropraxia or axonotmesis. High-energy trauma to an extremity with or without a fracture may produce a compartment syndrome. Nerve injury does not usually result from a direct electrical source. Typically, the energy is dissipated throughout the soft tissues and the nerve injury resolves more commonly from surrounding soft tissue swelling. Peripheral nerve compression may occur where the nerve passes through a tunnel and slides back and forth with joint flexion and extension. The upper extremity compression neuropathies are: pronator syndrome, anterior interosseous syndrome, carpal tunnel syndrome, thoracic outlet syndrome, cubital tunnel syndrome, Guyon's canal syndrome, posterior interosseous nerve syndrome, radial tunnel syndrome, and radial sensory nerve entrapment.