Swallowing(redirected from swallowing threshold)
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a complex reflex act in which food is carried from the oral cavity to the esophagus and stomach by the contraction of some muscles and the relaxation of others.
In vertebrates and man, the swallowing reflex arises upon stimulation of the sensitive endings of the trigeminal, superior and inferior laryngeal, and glossopharyngeal nerves in the mucous membrane of the soft palate. The swallowing center is located on the floor of the fourth ventricle in the medulla oblongata. The first phase of swallowing is voluntary. The lump of chewed food is pushed into the pharynx by movements of the cheeks and tongue. Contraction of the palatine arches and radix linguae, closure of the nasopharyngeal cavity, and covering of the entrance to the larynx by the epiglottis allow the bolus to be pushed only into the opening of the esophagus, whose peristaltic movements provide for its further passage. Swallowing ends with relaxation of the muscular closure and entrance to the stomach. Liquid passes through the esophagus under the influence of pressure created in the pharynx and its own weight.