Masticatory muscles physiology and functional anatomy

Abstract

Mouth dosage id est mandible lifting appears due to two-sided symmetric activity of masseters, temporal and medial pterygoid muscles though muscles work non-symmetrically, with their bigger activity at the working side during the mastication. The gravitation action to mandible is equaled with the temporal muscles positive tone. They say that the latest ones play important role in the mandible positioning in the space. Also masseters and medial pteryoid muscles are activated at the teeth dosage. Mouth opening or mandible lowering is performed due to suprahyoid muscles (digastric muscle anterior belly, omy-hyoid and mylohyoid one) with the lateral pterygoid muscles participance. Suprahyoideal muscles are attached to the mandible and hyoid bone. When hyoid bone is fixed due to subhyoid muscles than suprahyoid muscles can participate in mandible lowering. Mandible symmetric protrusion (movement forward) is achieved by lateral pterygoid muscles two-sided action. Mandible retrusion (movement back) is performed by temporal muscles posterior part, suprahyoid muscles and masseter deep fibers. Laterotrusion (mandible shift on the right or on the left) takes place at contralateral pterygoid muscle contraction as well as ipsylateral lateral pterygoid muscle contraction. Though laterotrusion is usually combined to the protrusion on opposite side while antero-lateral movement forming.