EMG is used to check muscles for nerve damage, and the extent of that damage. In medicine EMG is used to determine the functional status of peripheral nerves, neurons, neuromuscular junctions, and the muscles themselves. EMG is a recording of the electrophysiologic activity of a muscle at rest or under stimulation. It is the one that can be used to distinguish whether the muscle is neurogenic injury or myogenic injury, so that EMG is used to check for nerve injury. By determining the time limit, wave amplitude, the presence or absence of spontaneous electrical activity in a quiet state, and the wave pattern and wave amplitude produced when the muscles are vigorously contracted, it can be used to differentiate between neurogenic and myogenic damage, and to diagnose anterior poliomyelitis, motor neuron disease, and nerve root and peripheral neuropathy. EMG is also used to track the efficacy and degree of recovery during the treatment of various diseases. It is recommended that patients who have the need for the test consult with their doctors in a timely manner and choose the appropriate test under the doctor’s guidance.