Figure 1 - Diagrammatic illustration of motor events of swallowing reflex.

a. Illustrates the onset of the swallowing reflex. It shows tip of tongue in contact with anterior part of palate. Bolus is pushed backward in groove between tongue and palate. Soft palate is being drawn upward. b. Bolus has reached the vallecula. Hyoid bone and larynx move upward and forward. Epiglottis is tipped downward. Contraction wave on posterior pharyngeal wall moves downward. c. Soft palate has been pulled down and approximated to root of tongue by contraction of pharyngopalatine muscles, and by pressure of descending pharyngeal contraction wave. Cricopharyngeus muscle is opening to permit entry of bolus into esophagus. Trickle of food enters also laryngeal opening but is prevented from going farther by closure of ventricular folds. d. The contraction wave has reached vallecula and is pressing out last of bolus from them. The bolus has largely passed through the upper sphincter into esophagus. e. Contraction wave has passed pharynx. Epiglottis is beginning to turn up again as Hyoid bone and larynx descend. Communication with nasopharynx has been re-established. f. All structures of pharynx have returned to resting position. (Source: Netter medical illustrations with permission from Elsevier. All rights reserved.)