Electromyography (EMG) is an electrodiagnostic medicine technique for evaluating and recording the electrical activity produced by skeletal muscles. EMG is performed using an instrument called an electromyograph to produce a record called an electromyogram. An electromyograph detects the electric potential generated by muscle cells when these cells are electrically or neurologically activated. The signals can be analyzed to detect medical abnormalities, activation level, or recruitment order, or to analyze the biomechanics of human or animal movement.

A nerve conduction velocity (NCV) test is used to assess nerve damage and dysfunction. Also known as a nerve conduction study, the procedure measures how quickly electrical signals move through your peripheral nerves.
Your peripheral nerves are located outside of your brain and along your spinal cord. These nerves help you control your muscles and experience the senses. Healthy nerves send electrical signals more quickly and with greater strength than damaged nerves.
The NVC test helps your doctor differentiate between an injury to the nerve fiber and an injury to the myelin sheath, the protective covering surrounding the nerve. It can also help your doctor tell the difference between a nerve disorder and a condition where a nerve injury has affected the muscles.