esophagus

esophagus (ĭsŏf`əgəs), portion of the digestive tube that conducts food from the mouth to the stomach. When food is swallowed it passes from the pharynx into the esophagus, initiating rhythmic contractions (peristalsis) of the esophageal wall, which propel the food along toward the stomach. The walls of the esophagus are lined with mucous glands that continue the lubrication of the food as it is conducted to the stomach. The human esophagus is about 10 in. (25 cm) long and 1 in. (2.5 cm) in diameter. See digestive system.

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esophagus

Muscular tube that conveys food by peristalsis from the pharynx to the stomach. Both ends are closed off by sphincters (muscular constrictions), which relax to let food through and close to keep it from backing up. Disorders include ulceration and bleeding, heartburn from stomach acid, achalasia (failure of one or both sphincters to open), and muscle spasms. Scleroderma may involve the esophagus.

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oesophagus (US), esophagus

the part of the alimentary canal between the pharynx and the stomach; gullet

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Esophagus

A section of the alimentary canal that is interposed between the pharynx and the stomach. Because of divergent specializations in the various vertebrates, the esophagus cannot be described in general terms and is not always distinguishable.

In humans it is a tube running the full length of the neck and the thorax, held in its position ventral to the vertebral centra by a tunica adventitia of loose connective tissue. It has an inner lining of folded mucous membrane with an exceptionally thick lamina propria, a submucosa of elastic and collagenous connective tissue, and two layers of muscle. The musculature is striated in the anterior third of its length, unstriated in the posterior third, and variably intermixed in the middle. It is supplied with autonomic nerve fibers.

Although normally collapsed, the human esophagus is capable of considerable distension during the rapid passage of swallowed material, under which condition the folds of mucous membrane and lamina propria are temporarily smoothed out. Numerous microscopic esophageal glands open into the lumen, extending their compound tubules out into the submucosa.

In humans the transition from the esophagus to the stomach occurs quite abruptly at the diaphragm. The pharynx narrows posteriorly like a funnel and the foregut may thereupon enlarge, but much of what appears to be stomach may have an esophageal character histologically. See Digestive system