Coordination of Laryngeal Movements and Orofacial Muscle Activities in Swallowing.

Abstract

The purpose of the present study was to investigate the coordination between the muscle activities of the masticatory, facial and suprahyoid muscles, and the action of the oral, pharyngeal and laryngeal organs in healthy subjects during chewing and swallowing barium bread. Videofluorography (VF) and electromyography (EMG) were recorded while subjects took in, masticated and swallowed the barium bread.The following results were obtained: in the pharyngeal stage of swallowing, a monophasic wave was observed during laryngeal movement. The reproducibility was confirmed in the relationship between the laryngeal movement wave and bolus position when swallowing. The duration of muscle activity in the masticatory muscles, orbicular oris muscle and suprahyoid muscle during swallowing was significantly longer than in chewing. In the temporal relationship between laryngeal movement and muscle activities, the temporal and masseter muscles began the activities before the onset of the monophasic laryngeal movement, whereas the digastric and mylohyoid muscles were activat-ed almost simultaneously or slightly after onset.