Fig. 4.

The pooled average trajectories of the hyoid bone and epiglottic base left column. Arrow heads in each trajectory indicate the starting point. The hyoid movement trajectories during swallowing in a neutral (a), a comfortable chin-down (b), and a strict chin-tuck (c) posture are shown. The chin-tuck posture shows a marked reduction in hyoid excursion in the horizontal direction and a slight increase in the vertical direction (c). Right column. The trajectories of the epiglottic base during swallowing in a neutral (d), a comfortable chin-down (e), and a strict chin-tuck (f) posture are shown. The backward retraction and elevation of the epiglottic base is distinctively enhanced (f)