Tonic activity of the human temporalis muscle at mandibular rest position

Abstract

ObjectiveThere are two theories on the control of the human mandibular rest position; the visco-elastic theory and the muscular theory. In this study, we have searched for evidence for the muscular theory. DesignWe have investigated the activity of the anterior temporalis muscle during various positions of the mandible using intramuscular electrodes. ResultsIn nine out of ten subjects tonic activity in the anterior temporalis muscle during the mandibular rest position was observed. Most of these units ceased firing under the jaw dropped condition of the mandible. ConclusionsCurrent findings support the muscular theory since single motor unit activity during the rest position of the mandible is observed in the anterior temporalis. We do not however have any evidence against the visco-elastic theory which may contribute in part to maintain the rest position of the mandible.