Electromyography

Electromyography (EMG) refers to the electrical detection of signals arising from the depolarization of skeletal muscle. These signals may be detected from skin surface electrodes or from needles placed directly within the muscle. These two types of recordings are used for different purposes, with needle recording used to detect the behavior of individual muscle fibers and motor units while surface recordings are used to detect overall muscle activity in particular positions or actions. Surface EMG is not a common clinical procedure, though it may be used in rehabilitation. Needle electromyography is used to determine whether there is damage to nerve fibers to individual muscles.