Nerve conduction velocity (NCV) is a test to see how fast electrical signals move through a nerve. This test is done along with electromyography (EMG) to assess the muscles for abnormalities. The nerve conduction velocity test is performed to evaluate nerve function. It tests the speed impulses travel through a nerve. This test is also 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 start where the nerve root takes off from the 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 NCV 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. Making these distinctions is important for proper diagnosis and determining your course of treatment.