ABSTRACT
Peripheral nerves are bundles of axons conducting motor impulses from cells in the anterior horn of the spinal cord to the muscles, and sensory impulses from peripheral receptors via cells in the posterior root ganglia to the cord. They also convey sudomotor and vasomotor fibres from ganglion cells in the sympathetic chain. Some nerves are predominantly motor, some predominantly sensory; the larger trunks are mixed, with motor and sensory axons running in separate bundles. Nerves may be damaged by compression, stretching, laceration, thermal injury or chemical injury. Seddon's description of the three different types of nerve injury (neurapraxia, axonotmesis and neurotmesis) served as a useful classification for many years. If there is persistent conduction seen in the nerve segment distal to injury, then the lesion is non-degenerative. The final common pathology of all these mechanisms is nerve ischaemia. Peripheral neuropathy associated with generalized disorders such as diabetes or alcoholism may render a nerve more sensitive to the effects of compression.
