has part has part characteristic of has modifier peripheral nervous system neuron transmission of nerve impulse Abnormality of peripheral nerve conduction A nerve conduction study (NCS) is commonly conducted together with electromyography in order to evaluate muscle disorders. For the NCS, dermal electrodes are placed at intervals over the nerve to be examined, and a low-intensity current is introduced to generate action potentials. The velocity of the action potential is related to the diameter of the nerve fiber and the presence of a myelin sheath. Diseases of the myelin sheath characteristically reduce the nerve conduction velocity (NCV). The amplitude of the response is also measured. Abnormal cellular phenotype Abnormality of peripheral nervous system electrophysiology quality abnormal