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.

Related Terms

  • Muscle contraction
  • Neuromuscular junction
  • Action potential
  • Motor cortex


  • Motor neuron unit
  • Motor nerve unit
  • Motor endplate unit
  • Motor unit