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The esophagus (also spelled oesophagus/œsophagus), or gullet is the muscular tube in vertebrates through which ingested food passes from the mouth area to the stomach. The esophagus is continuous with the laryngeal part of the pharynx at the level of the C6 vertebra.
Function Food is passed through the esophagus by using the process of peristalsis. Specifically, in mammals, it connects the pharynx, which is the body cavity that is common to the digestive system and respiratory system behind the mouth (buccal cavity), with the stomach, where the second stage of digestion is initiated (the first stage of digestion is in the mouth, with teeth and tongue masticating food and mixing it with saliva). The esophagus is lined with mucous membrane, and is more deeply lined with muscle that acts with peristaltic action to move swallowed food down to the stomach. Histology The esophagus is lined by stratified squamous epithelium, which is rapidly turned over, and serves a protective effect due to the high volume transit of food, saliva and mucous into the stomach. The lamina propria of the esophagus is sparse. The mucous secreting glands are located in the submucosa, as are connective structures termed papillae. The muscularis propria of the esophagus consists of striated muscle in the upper third (or superior) part of the esophagus. The middle third consists of a combination of smooth muscle and striated muscle, and the inferior third is predominantly smooth muscle. The esophagus has a rich lymphatic drainage as well. Gastroesophageal junction The junction between the esophagus and the stomach (the gastroesophageal junction or GE junction) is not actually considered a valve, although it is sometimes called the cardiac valve, cardia or cardias, but is actually more of a stricture. Many people experience acid reflux, where stomach acid gets pushed up into the esophagus, causing a burning sensation, commonly termed heartburn. Extended exposure to heartburn may erode the lining of the esophagus, leading to a potentially cancerous condition called Barrett's Esophagus. Some people also experience a sensation known as globus esophagus, where it feels as if a ball is lodged in the lower part of the esophagus. Etymology The word "esophagus" is the result of the "o" being dropped from the oe (or œ) in "oesophagus". It derives from Greek; οiσω -oeso, future tense of the verb φερω-to bring and from the verb έφαγον,-phagus, past tense of τρώγω-to eat. Esophageal diseases and conditions The following are diseases and conditions that affect the esophagus: | |||||||||||||||||||||||||||||||||
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