Modulation of tongue motion and tongue pressure during liquid swallowing with different bolus volumes.

Abstract

The tongue functions by modulating according to bolus volume when swallowing; however, associated tongue dynamics are unclear. We aimed to clarify how tongue motion and tongue pressure change with bolus volume during swallowing. Sixteen healthy volunteers (age 29.5±3.8years; 12males, 4 females) were recruited. Two electromagnetic articulography markers were attached, one each on the anterior and posterior parts of the tongue, to measure motion. A sensor sheet, with five pressure-sensitive points, was attached to the hard palate to measure tongue pressure. Participants were asked to swallow 3ml and 10ml of water. Motion trajectory, maximum velocity, vertical displacement just before contact with the hard palate, and maximum magnitude and duration of tongue pressure were analysed. Tongue rotation was observed in the sagittal plane; its rate of appearance was significantly higher when swallowing 3ml of water than when swallowing 10ml, and the rate of rotation at posterior part was significantly higher than at the anterior part. The maximum velocity and vertical displacement were significantly greater when swallowing 10ml of water than those when swallowing 3ml of water. There was no significant difference in either the maximum magnitude of tongue pressure or maximum duration of tongue pressure between 3ml and 10ml. Bolus volume influenced the pattern of tongue motion; however, there was no difference in tongue pressure.