Motor unit

Motor Unit: One nerve fiber (nerve cell axon) and all of the muscles cells (fibers) it innervates.

• Example - Although a single muscle cell must fire completely or not at all, force output can be calibrated by the number and size of motor units recruited.

1. Saladin, K. (2012). Anatomy & Physiology: The unity of form and function. (6th ed.). New York: McGraw-Hill.