Biomechanics of human tongue movement during bolus compression and swallowing

We evaluated the effects of gel consistency and bolus volume on ingestion in humans. Eight healthy men were asked to ingest liquids, and sample foods of different gel consistencies and volumes, as usual. Tongue pressure against the hard palate was recorded at five points, and bolus flow was recorded using videoendoscopic images. The number of squeezes increased as gel consistency and volume increased. The integrated magnitude of tongue pressure during squeezing increased with increasing gel consistency. Bolus propulsion into the pharynx was affected by bolus characteristics, and location of the bolus head at the onset of pharyngeal swallowing was not related to squeezing behavior. The trigger point at which pharyngeal swallowing began was subject-dependent. During swallowing, the magnitude of tongue pressure moderately increased with increasing gel consistency, as compared with squeezing. Tongue pressure was not related to bolus volume. The current results suggest that patterns of tongue pressure during squeezing and swallowing are differentially affected by bolus conditions. However, healthy subjects differed in the techniques used for squeezing and swallowing.