electromyogram (EMG) /ilek′trōmī″əgram′/ , a record of the intrinsic electric activity in a skeletal muscle. Such data aid the diagnosis of neuromuscular problems and are obtained by applying surface electrodes or by inserting a needle electrode into the muscle and observing electric activity with an oscilloscope and a loudspeaker. Some electromyograms show abnormalities, such as spontaneous electric potentials within the muscle under study, and help pinpoint lesions of motor nerves. Electromyograms also measure electric potentials induced by voluntary muscular contraction. See also electroneuromyography.
