Figure 15 - Electromyography (EMG) responses of the opening and closing muscles of the UES during belching and swallowing activated by injection of 100 mL of air into the stomach of a chronically instrumented dog.

Note that the only anteriorly directed UES opening muscle activated during belching is the TH and the main UES opening muscle activated is the posteriorly directed StP. These muscle responses are consistent with the movement of the hyoid during belching (90). StP, stylopharyngeus, GH, geniohyoideus; TH, thyrohyoideus; CP, cricopharyngeus; ESO, esophagus 1 cm below the CP; SH, sternohyoideus.