Tongue-pressure and hyoid movement timing in healthy liquid swallowing

We hypothesized that tongue-palate pressure generation might directly facilitate hyoid movement in swallowing through the anatomical connections of the extrinsic tongue muscles. If true, noninvasive measures of tongue-palate pressure timing might serve as a proxy measure of hyoid excursion. We explored the timing lationships between events in the tongue-palate pressure and hyoid movement profiles during water and nectar-thick liquid swallowing in healthy adults. Concurrent intra-oral manometry and submental B-mode midsagittal ultrasound were recorded. We determined that there is no obligate sequence in the onsets, or offsets, of tongue-palate pressures and hyoid excursion. Timing lags (either of hyoid movement lagging tongue-palate pressures, or vice versa) fell within ½ second, on average. We conclude that tongue-palate pressure generation and hyoid movement are separate phenomena in the swallowing sequence and that non-invasive measures of tongue-pressure timing cannot be used reliably as proxy measures of hyoid movement timing