Electromyography (EMG) is used during spine surgery to monitor the peripheral, lumbar, and cranial nerves. By monitoring the muscles which are stimulated by these nerves, it can be determined if a nerve root is being irritated or disturbed during the procedure. If a nerve root of the peripheral, lumbar, or cranial nerves is irritated in any way (bumping, stretching, etc.) during surgery, the nerve will depolarize, causing an action potential which in turn causes the corresponding muscle to twitch. The twitch is recorded by electrodes used to monitor TCMEP, and immediate feedback is sent to the surgeon via the technologist.