Bolus aggregation in the oropharynx does not depend on gravity

Objective: To determine whether bolus aggregation in the oropharynx (before swallowing) depends on gravity. Design: Before-during trial, with subjects serving as their own controls. Setting: Hospital radiology suite. Participants: Five asymptomatic adult volunteers. Interventions: Videofluorography was performed while subjects ate soft and hard foods containing barium, first seated upright and then kneeling face down (quadruped position). Main Outcome Measures: Duration of food processing in the oral cavity, bolus aggregation in the valleculae, and pharyngeal swallow. Results: Transport of chewed solid food from the oral cavity to the oropharynx (stage II transport) typically started several seconds before onset of swallow, regardless of head position or initial food consistency. Bolus aggregation in the valleculae (between the epiglottis and the tongue) began an average of 1.7 ± 2.5sec before the onset of the pharyngeal swallow ( p < .001). Stage II transport was driven by tongue-palate contact. Conclusions: Transport of chewed solid food from the oral cavity to the pharynx is driven actively by tongue-palate contact and does not depend on gravity. A bolus may accumulate in the valleculae for several seconds before the swallow.