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| Cardia | |
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| Diagram from cancer.gov: * 1. Body of stomach * 2. Fundus * 3. Anterior wall * 4. Greater curvature * 5. Lesser curvature * 6. Cardia * 9. Pyloric sphincter * 10. Pyloric antrum * 11. Pyloric canal * 12. Angular notch * 13. Gastric canal * 14. Rugal folds |
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| Diagram of the stomach, showing its anatomical landmarks ("Antrum cardiacum" marks the opening of the cardia). | |
| Gray's | subject #247 1162 |
The cardia (also known as Z-line or esophagogastric junction[1] or gastroesophageal junction[2][3][4][5]) 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 the site of the lower esophageal sphincter (LES)[6][7][8] (also termed cardiac sphincter[9], gastroesophageal sphincter, and esophageal sphincter[10]).
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Nomenclature and classification
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. The difference is more than semantic when used in clinical studies and applied to individual patients.
Classical anatomy textbooks, and some other resources[11], 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.
Many recent writings describe it as the esophageal sphincter.
Function
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 esophageal sphincter (ES), and prevents gastric juice from flowing back into the esophagus.
During peristalsis, the ES allows the food bolus to pass into the stomach. It prevents chyme, a mixture of bolus, stomach acid, and digestive enzymes, from returning up the esophagus. The ES is aided in the task of keeping the flow of materials in one direction by the diaphragm.
Histology
On histological examination, the junction can be identified by the following transition:[12][13]
- nonkeratinized stratified squamous epithelium in the esophagus
- simple columnar epithelium in the stomach
However, in Barrett's esophagus, the epithelial distinction may vary, so the histological border may not be identical with the functional border.
The cardiac glands can be seen in this region. They can be distinguished from other stomach glands (fundic glands and pyloric glands) because the glands are shallow and simple tubular.
Pathology
Deficiencies in the strength or the efficiency of the LES lead to various medical problems involving acid damage on the esophagus.
In achalasia, one of the defects is failure of the LES to relax properly.
Removal
Surgical removal of this area is a called a cardiectomy a term that is also used to describe removal of the Heart. [14][15][16]
Etymology
The word comes from the Greek kardia meaning heart, the cardiac orifice of the stomach.
See also
- Artificial cardia, that can be used to fight, between other diseases, esophageal cancer, achalasia and gastroesophageal reflux disease.
Additional images
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 Section of mucous membrane of human stomach, near the cardiac orifice. X 45. |
References
- ^ esophagogastric+junction at eMedicine Dictionary
- ^ MedEd at Loyola Radio/curriculum/GI/Image105b.jpg
- ^ Lab Exercises- Esophagus
- ^ ACS :: What Is Cancer of the Esophagus?
- ^ Definition of gastroesophageal junction - NCI Dictionary of Cancer Terms
- ^ Digestive Disease Library
- ^ Department of Physiology and Cell Biology
- ^ med/2965 at eMedicine
- ^ cardiac+sphincter at eMedicine Dictionary
- ^ Patient Handout: Gastroesophageal Reflux Disease (GERD)
- ^ SUNY Labs 37:06-0103 - "Abdominal Cavity: The Stomach"
- ^ Histology at BU 11101loa
- ^ Histology at BU 11111ooa
- ^ cardiectomy at dictionary.reference.com
- ^ O. W. BARLOW. "THE SURVIVAL OF THE CIRCULATION IN THE FROG WEB AFTER CARDIECTOMY" (web). Journal of Pharmacology And Experimental Therapeutics, Vol. 35, Issue 1, 17-24, 1929. Retrieved on Feburuary 24, 2008.
- ^ S.J. MELTZER (1913). THE EFFECT OF STRYCHNIN IN CARDIECTOMIZED FROGS WITH DESTROYED LYMPH HEARTS. American Journal of Physiology, Page xix.
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Wikipedia content modification information:
- This page was last modified on 4 October 2008, at 20:56.
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