Electromyography is a common means of examining nerve damage. The two electrodes of the instrument are connected in series with the nerve itself to form a closed circuit, and as long as there is an overcharge condition, it means that the continuity of the nerve is still there, and the severity of the nerve damage is judged by the intensity of the current itself, and if there is no overcharge condition at all, it means that the nerve is completely broken. The normal test is to put two electrodes at the distal and proximal ends of the nerve, the distal end is a receiving electrode and the proximal end is a stimulating electrode to see the current overcharge.