Tetanic contraction

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A tetanic contraction (also called tetanized state, tetanus, or physiologic tetanus, the latter to differentiate from the disease called tetanus) is a sustained muscle contraction[1] evoked when the motor nerve that innervates a skeletal muscle emits action potentials at a very high rate.[2][3] During this state, a motor unit has been maximally stimulated by its motor neuron and remains that way for some time. This occurs when a muscle's motor unit is stimulated by multiple impulses at a sufficiently high frequency. Each stimulus causes a twitch. If stimuli are delivered slowly enough, the tension in the muscle will relax between successive twitches. If stimuli are delivered at high frequency, the twitches will overlap, resulting in tetanic contraction. When tetanized, the contracting tension in the muscle remains constant in a steady state. This is the maximal possible contraction.[2] During tetanic contractions, muscles can shorten, lengthen or remain constant length.[4]

Muscles may exhibit some level of tetanic activity, leading to muscle tone, in order to maintain posture.[5]

See also[edit]


  1. ^ "Tetanic". The American Heritage Medical Dictionary. Boston Massachusetts: Houghton Mifflin Company. 2007. p. 815. ISBN 978-0-618-82435-9. Marked by sustained muscle contractions 
  2. ^ a b Mann MD (2011). "Chapter 14: Muscle Contraction: Twitch and tetanic contractions". The Nervous System In Action. Michael D. Mann. 
  3. ^ Lombard JH, Rush NJ (2003). "Cells, Nerves, and Muscles". In Raff H. Physiology Secrets (2nd ed.). Philadelphia, PA: Hanley & Belfus. pp. 25–26. ISBN 978-1-56053-509-6. 
  4. ^ Widmaier EP, Raff H, Strang KT (2010). "Muscle". Vander's Human Physiology: The Mechanisms of Body Function (12th ed.). New York, NY: McGraw-Hill. pp. 250–291. ISBN 0-321-98122-7. 
  5. ^ Davidoff RA (1992). "Skeletal muscle tone and the misunderstood stretch reflex". Neurology 42 (5): 951–63. doi:10.1212/WNL.42.5.951. PMID 1579249.