Process of graphically recording the electrical activity of muscle, which normally generates an electric current only when contracting or when its nerve is stimulated.
Electrical impulses are shown as wavelike tracings on an oscilloscope and recorded as an electromyogram (EMG), usually along with audible signals. The EMG can show whether muscle weakness or wasting is due to nerve impairment (as in poliomyelitis ) or muscle impairment or disease (myopathy).