Change in palatoglossus muscle activity in relation to swallowing volume during the transition from the oral phase to the pharyngeal phase.

The purpose of this study was to examine whether the palatoglossus (PG) muscle is involved in the regulation of function during the transition from the oral to the pharyngeal phase. Seven normal adults participated in the study. Smoothed electromyography (EMG) signals of the PG muscle and levator veli palatini (LVP) muscle were collected. Each subject swallowed water at five different volumes: 12.5%, 25%, 50%, 100%, and 150% (or 200%) of his/her optimum swallowing volume. PG muscle waveform showed two patterns of activity: one of a single peak and the other of two peaks. There was no significant difference (p < 0.01) in the timing of emergence between the single peak and the second peak of the two-peak pattern. There were two patterns of PG muscle activity in response to a change in swallowing volume, i.e., one was a pattern in which the activity was correlated to the change in swallowing volume, the other was a pattern in which the activity was not changed but almost at the maximum activity level, irrespective of swallowing volume. We conclude that the PG muscle could be involved in the regulation of swallowing from the oral to the pharyngeal phase. The activity could be influenced by swallowing volume.