swallowing
n. the process by which ingested material (food, liquid, etc.) is transferred from the mouth cavity to the stomach, which involves a complex series of reflex muscle contractions and relaxations. The muscles of the cheeks, tongue, and roof of the mouth first contract to form a chute, after which the tongue presses upward and backward against the hard palate. As the substance to be swallowed passes toward the back of the mouth, the soft palate is raised to close the opening to the nasopharynx. At the same time, the epiglottis is lowered over the opening to the trachea (windpipe) to prevent food or fluid entering the respiratory system, and the larynx moves upward to form a seal against the lower side of the epiglottis. As the substance swallowed enters the esophagus, it is moved along by alternate contractions of two layers of muscles (composed of, respectively, longitudinal and circular muscle fibers) so that the food or fluid is advanced toward the stomach,
regardless of body position. Also called deglutition.