Electromyography is a test that measures muscle response to nervous stimulation. A needle electrode is inserted through the skin into the muscle. Each muscle fiber that contracts will produce an action potential. The presence, size, and shape of the wave form of the action potential produced on the oscilloscope, provides information about the ability of the muscle to respond to nervous stimulation.
Review Date 11/2/2018
Updated by: Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.