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
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.