Characteristics of the Perioral Muscle Electromyographic Activities during Jaw Functions in Healthy Young Adults

Purpose: The aim of the present study was to record the electromyographic (EMG) activity of the mentalis muscle (Ment) during various jaw functions in healthy young subjects.Methods: Twelve healthy males were enrolled for the study. A portable EMG recording device was used to record the EMG activity from the Ment, anterior belly of the digastric muscle (Dig), and the masseter (Mm) muscles. The EMG activities of these muscles were recorded during maximal voluntary clenching (MVC), maximal voluntary jaw opening (MVO), and the masticatory process. The EMG activity of Ment was compared with the EMG activities of Dig and Mm during various jaw functions.Results: (1) The EMG activities of Ment and Dig were significantly greater during MVO than during MVC (P<0.05). A strong correlation was found between the activities of Ment and Mm during MVO (r=0.739, P<0.01), and between those of Ment and Dig during MVC (r=0.664, P<0.05). (2) It was observed that during mastication of peanuts, Ment showed synchronous activity with that of Dig and reciprocal activity with that of Mm.Conclusion: These results indicate that Ment acts in coordination with the actions of Dig and Mm during various jaw functions.