Motor Unit
Motor Unit: One nerve fiber (nerve cell axon) and all of the muscles cells (fibers) it innervates. For 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.
- Saladin, K. (2012). Anatomy & Physiology: The unity of form and function. (6th ed.). New York: McGraw-Hill.