Protrusion• Lateral pterygoid assisted  by medial pterygoidRetraction• Posterior fibers of temporalis,  deep part of masseter, and  geniohyoid and digastricDepression• Gravity• Digastric, geniohyoid, and  mylohyoid musclesElevation• Temporalis, masseter,  medial pterygoid
Fig. 8.141 Masseter muscle.