Fig. 4: The classes 3 (left), 1 (middle) and 2 (right) lever systems of the vertical phase of closure of the human unilateral chewing cycle. | BDJ Open

Fig. 4: The classes 3 (left), 1 (middle) and 2 (right) lever systems of the vertical phase of closure of the human unilateral chewing cycle.

From: The reciprocal jaw-muscle reflexes elicited by anterior- and back-tooth-contacts—a perspective to explain the control of the masticatory muscles

Fig. 4

The food bolus is located at the left first molar. The fulcrums corresponding for the class 3, 1 and 2 levers (the FUL3, FUL1 and FUL2, respectively) are encircled. The large arrows designate the active force vectors of the temporal (1) and masseter muscles (2). Instantaneous changes in the resiliency of the food bolus determines the power of the class 1 lever (middle). The class 1 lever system may cause distraction of the FUL3, or hasten the tipping of the anterior part of mandible for ANT contacts.

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