Electromyograph [EMG] is a test used to discover diseases of the muscles, spinal cord, and peripheral nerves by measuring how electrical current moves through them.

a medical instrument that records the electrical waves associated with the activity of skeletal muscles

a test that measures the electrical activity in the muscles to determine the amount of muscle tension. Small, flat metal sensors, called electrodes, are attached to the skin (usually on the forehead). The electrodes measure the electrical activity in the muscles directly underneath the electrodes and adjoining muscles. The electrical activity of the muscles will be measured and displayed as numbers or electrical waves on a screen that the person can view.