An Electromyogram (EMG) measures the electrical activity of muscles at rest and during contraction to check the health of muscles and nerves controlling the muscle. EMGs are typically conducted when a person has symptoms of weakness, pain or abnormal sensation. The test helps differentiate muscle weakness caused by nerve injury from weakness due to nervous system disorder.
During the test, thin needle electrodes are inserted through the skin and into the muscle. The electrodes will record any electrical activity given off by the muscles.