Electromyography (EMG) is a procedure that assesses the health of muscles and the nerve cells that control them. It can reveal nerve and muscle dysfunction. The nerve cells that control muscles are called motor neurons. Motor neurons are responsible for sending electrical signals that cause a muscle to contract. An EMG makes these signals visible either in graphs or numerical format that can be interpreted by one of our providers. Electrodes inserted directly into the muscle transmit or detect signals and records them. A nerve conduction study uses electrodes taped to the skin to measure the speed and strength of electrical signal between two places on the body.