The cardia is the anatomical term for the junction orifice of the stomach and the esophagus. At the cardia, the mucosa of the esophagus transitions into gastric mucosa.

The cardia is also called the Lower Esophageal Sphincter (LES), cardiac sphincter and gastroesophageal sphincter. The word comes from the Greek kardia meaning heart, the cardiac orifice of the stomach.

There is disagreement in the academic anatomy community over whether the cardia is part of the stomach, part of the esophagus or a distinct entity, as described in this article. Classical anatomy textbooks describe the cardia as the first of 4 regions of the stomach. This makes sense histologically because the mucosa of the cardia is the same as that of the stomach. Recent writings describe it as the LES. The difference is more than semantic when used in clinical studies and applied to individual patients. See two discrepant diagrams below to illustrate the controversy. The first diagram shows a stomach with 3 regions and a cardia, presumably referring to the LES. The second shows 5 regions of the stomach, including the cardia.

The stomach generates strong acids and enzymes to aid in food digestion. This digestive mixture is called gastric juice. The inner lining of the stomach has several mechanisms to resist the effect of gastric juice on itself, but the mucosa of the esophagus does not. The esophagus is normally protected from these acids by a one-way valve mechanism at its junction with the stomach. This one-way valve is called the lower esophageal sphincter (LES), and prevents gastric juice from flowing back into the esophagus.

Artificial cardia

The Shanghai No. 9 People's Hospital affiliated to the No. 2 Medical Sciences University has successfully transplanted artificial cardia. The hospital developed the artificial cardia with metallic and macromolecule materials.

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