Pattern of tongue pressure on hard palate during swallowing

Contact of the tongue against the hard palate plays an important role in swallowing. This study aimed to clarify the pattern of contact between the tongue and hard palate by analyzing tongue pressure produced in swallowing 15 ml of water by healthy subjects wearing an experimental palatal plate with seven pressure sensors. Tongue pressure was generated initially by close contact with the anteriomedian part of the hard palate, then with the circumferential part, and finally softly with the posteriomedian part. Tongue pressure reached a peak quickly, then decreased gradually before disappearing almost simultaneously at each measured part of the hard palate. Magnitude and duration were significantly larger in the anteriomedian part compared to the other six parts measured, and was significantly smaller in the posteriomedian part. No laterality was found in tongue pressure produced at the circumferential parts of the hard palate. Our findings indicate that the order of tongue contact against each part of the hard palate as well as duration and magnitude of tongue pressure are coordinated precisely during swallowing. These findings could aid assessment of the tongue movement of dysphagic patients during rehabilitation.