Esophagus

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Esophagus
The position and relation of the esophagus in the cervical region and in the posterior mediastinum. Seen from behind.
Section of the human esophagus. Moderately magnified. The section is transverse and from near the middle of the gullet. a. Fibrous covering. b. Divided fibers of longitudinal muscular coat. c. Transverse muscular fibers. d. Submucous or areolar layer. e. Muscularis mucosae. f. Mucous membrane, with vessels and part of a lymphoid nodule. g. Stratified epithelial lining. h. Mucous gland. i. Gland duct. m’. Striated muscular fibers cut across.
Latin	oesophagus
Gray's	subject #245 1144
MeSH	A03.556.875.500
Dorlands/Elsevier	e_16/12343479

The esophagus (also spelled oesophagus/œsophagus), or gullet is an organ in vertebrates which consists of a muscular tube through which 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.

[edit] 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.

[edit] 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.

[edit] 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.

[edit] 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.

[edit] Esophageal diseases and conditions

The following are diseases and conditions that affect the esophagus:

• Achalasia
• Chagas disease
• Caustic injury to the esophagus
• Esophageal atresia and Tracheoesophageal fistula
• Esophageal cancer
• Esophageal spasm
• Esophageal speech
• Esophageal stricture
• Esophageal varices
• Esophageal web
• Esophagitis
• GERD
• Hiatus hernia
• Mallory-Weiss syndrome
• Neurogenic dysphasia
• Plummer-Vinson syndrome
• Schatzki's ring
• Zenker's diverticulum

[edit] Additional images

H&E stain of biopsy of normal esophagus showing the stratified squamous cell epithelium

Section of the neck at about the level of the sixth cervical vertebra.

[edit] External links

• Virtual Slidebox at Univ. Iowa Slide 449