Bilateral experimental muscle pain changes electromyographic activity of human jaw-closing muscles during mastication

Exp Brain Res. 1997 Aug;116(1):182-5. doi: 10.1007/pl00005738.


The effects of bilateral experimental muscle pain on human masticatory patterns were studied. Jaw movements and electromyographic (EMG) recordings of the jaw-closing muscles were divided into multiple single masticatory cycles and analyzed on a cycle-by-cycle basis. In ten men simultaneous bilateral injections of hypertonic saline (5%) into the masseter muscles caused strong pain (mean+/-SE: 7.5+/-0.4 on a 0-10 scale), significantly reduced EMG activity of jaw-closing muscles in the agonist phase, and significantly increased EMG activity in the antagonist phase. Nine of the subjects reported a sensation of less intense mastication during pain. Injections of isotonic saline (0.9%) did not cause pain or significant changes in masticatory patterns. The influence of higher brain centers on conscious human mastication can not be discarded but the observed phase-dependent modulation could be controlled by local neural circuits and/or a central pattern generator in the brain stem which are capable of integrating bilateral nociceptive afferent activity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Electromyography
  • Humans
  • Male
  • Mastication / physiology*
  • Masticatory Muscles / physiopathology*
  • Pain / physiopathology*