Swallowing (redirected from swallowing threshold)

swallowing

 or deglutition

Act that moves food from the mouth to the stomach. The tongue pushes liquid or chewed food mixed with saliva into the pharynx. Reflex takes over as the soft palate rises to close off the nasal cavity; the larynx rises and the epiglottis covers the trachea, interrupting breathing. Pressure in the mouth and pharynx pushes food toward the esophagus, whose upper sphincter opens to let food in and closes to prevent backflow. Breathing resumes as the larynx lowers. As peristalsis pushes food to the stomach, the lower esophageal sphincter opens and then closes to prevent reflux. Painful swallowing is usually caused by inflammation; other problems are caused by blockage or disorders affecting the motions of swallowing.

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Swallowing 

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.