EMG is used to examine and measure the muscle activity. This test is performed by a neurologist. A thin needle is inserted into the weak muscle and the muscle activity is assessed. The type as well as the origin of muscle weakness is identified which may be the muscle itself or the nerve tracts which activate the muscle. This information is very helpful in accurate diagnosis and management of the patient. This test is very helpful in patients with any type of muscle disorder, motor neuron disease and various nerve lesions.