Figure 14 - Temporal relationship among function of the glottis, UES, hyoid bone, and esophageal and stomach pressures during belching induced by rapid injection of 40 mL of air into the esophagus.

This figure is based on data obtained from concurrent recordings of videoendoscopic, videofluoroscopic, manometric, and electromyographic data. Belch begins with vocal cord adduction and ends with return to resting position. All other events, including UES opening and closure, occur while cords are fully adducted and thereby introitus to trachea is closed. VC-Ad-O, onset of vocal cord adduction; VC-Ab-Max, maximum onset of vocal cord adduction; VC-Ab-O, onset of vocal cord abduction; VC-Ab-Max, return of vocal cords to resting position; EPI-O, onset of increase in intraesophageal pressure; AEA-O, onset of approximation of arytenoids toward base of epiglottis; GPI-O, onset of increase in intragastric pressure; EMG-O, onset of EMG response from geniohyoid/mylohyoid muscle group; UESR-O, onset of UES relaxation. (Source: Shaker et al.,¹⁰⁶ with permission of the American Physiological Society.)