Mandibular opening

The digastric,mylohyoid and geniohyoid muscles are active during jaw opening either slowly or maximally against resistance.No activity occurs in the temporalis and masseter muscles while the mouth is opened slowly and when the jaw is opened maximally,some activity may occur in the medial pterygoid muscle.When the jaw is opened against resistance,the temporalis muscle remains silent.During opening movements,the lateral pterygoid muscles show initial and sustained activity.In forced depression,the digastric muscle is activated almost as soon as the lateral pterygoid muscle is.The activity of the anterior digastric muscle follows that of the lateral pterygoid muscle.