An electromyogram (EMG) is a test that measures the electrical discharges made by the muscles. It can determine whether muscle weakness or paralysis is due to a nerve problem or to a problem with the muscle itself.

During an electromyogram, a thin needle is placed in a muscle to measure its electrical activity at rest and during use. The needle is attached to a machine with a viewing screen (like a TV) that displays electrical activity in the muscles as waves on the screen.

By	Healthwise Staff
Primary Medical Reviewer	Anne C. Poinier, MD - Internal Medicine
Specialist Medical Reviewer	Colin Chalk, MD, CM, FRCPC - Neurology
Last Revised	July 26, 2010