Contribution of the digastric muscles to the control of bite force in man

J.D. van Willigen, E. Otten, Geranda Slager, M.L. Broekhuijsen

Research output: Contribution to journalArticleAcademicpeer-review


The contribution of the (co-contracting) digastric muscles to the rapid decline in bite-force magnitude after unloading of a static bite was investigated by asking participants to perform two different biting tasks with sudden unloading, and correlating the degree of co-contraction of the digastrics (as derived from their electromyograms) with the impact force, the impact velocity (as measured after a travel distance of 5 mm), and the residual force when the jaw system was in static conditions again after the impact. Co-contraction of the digastrics was varied by asking participants to perform the biting task while controlling bite force (force-controlled experiments) or jaw position (position-controlled experiments). In half of the experiments, participants co-contracted their digastrics more strongly in the position-controlled than the force-controlled experiments. However, there was no clear relation between the level of co-contraction and the magnitude of the impact force, the impact velocity and the residual force. The results imply that co-contraction of the digastric muscles is not sufficient to explain the reduction in bite force and the low impact velocity after an unexpected jaw-closing movement. Two other possible mechanisms that reduce forces in an unloaded jaw system are: (1) force velocity properties of the activated jaw muscles in conjunction with creep of the aponeurotic sheets of the jaw muscles, resulting in a slow partial recovery of the biting force after impact: (2) force length properties of jaw-opening muscles, an activity not recorded here.
Original languageEnglish
Pages (from-to)45-56
JournalArchives of Oral Biology : an international journal
Issue number1
Publication statusPublished - 1 Jan 1997
Externally publishedYes


  • digastric muscles
  • jaws
  • bite force


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