Electromyography Overview

Definition

Electromyography is a test that assesses the health of the muscles and the nerves controlling the muscles.

Other Names

EMG; Myogram

How the Test is Performed

For an EMG, a needle electrode is inserted through the skin into the muscle. The electrical activity detected by this electrode is displayed on an oscilloscope, and may be heard through a speaker.

After placement of the electrodes, you may be asked to contract the muscle (for example, by bending your arm). The presence, size, and shape of the wave form -- the action potential -- produced on the oscilloscope provide information about the ability of the muscle to respond when the nerves are stimulated.