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Abstract The geniohyoid, anterior belly of digastric, mylohyoid, and genioglossus muscles of 20 human subjects were studied electromyographically to determine the temporal relationships of their activities during the act of swallowing. Although the firing order of the four muscles varied within the same subject, the best estimate of the “true” firing sequence was established for each of the 18 subjects who provided statistically significant data. However, no definite universal pattern could be established for the four muscles because there was great inter‐subject variability in both the duration and the sequence of activity. Therefore, at least with respect to these four muscles, each individual has his own swallowing pattern, but different people may swallow quite differently. The type of bolus (saliva vs water) may influence the duration of the muscles' activity. On the other hand, posture (semi‐reclined vs sitting) did not seem to have any influence. There was no evidence to indicate that posture and/or the type of bolus are correlated with the sequence of muscular activity. The anterior belly of the digastric muscle was not active in one‐quarter of the swallows studied. When active during deglutition, all muscles had a general electromyographic pattern of one to many summations of activity separated by relatively quiet periods before and after each swallow.
Hrycyshyn et al. (1972) studied this question.