What is Myoelectric Potential?

Myoelectric potential is an action potential generated when muscle cells (muscle fibers) of an organism contract.

An electromyogram (Electro Myo Graphy – EMG) is a graph recording changes of weak electric field in muscles on the vertical axis and the passage of time on the horizontal axis.

Since myoelectric potential enables to read movements of human muscles, it is applied for the operation of prosthetic hands, powered suits, rehabilitation and sports engineering.

The processes of measuring myoelectric potential are described below, from the mechanism how muscle operates to the method of capturing a weak electric field.

Mechanism of Muscle Movement

α motor neurons in the spinal cord are activated by commands of muscle activity from the brain. At that time, a nerve impulse is transmitted through nerve axons to the muscle to be moved.

As shown in the figure on the right, nerve axons are branched and connected to many muscle fibers inside the muscle. This junction is called the neuromuscular junction.

Each muscle fiber has one neuromuscular junction, and each motor neuron is connected to multiple muscle fibers. In other words, there are multiple muscle fiber groups by one axon, which are called motor units.