Editing Esophagus (section)

===Gastroesophageal junction===
The gastroesophageal junction (also known as the esophagogastric junction) is the junction between the esophagus and the stomach, at the lower end of the esophagus.<ref>{{Cite encyclopedia|title=Stedman's Concise Medical and Allied Health Dictionary|editor= John H. Dirckx|year=1997|isbn=978-0-683-23125-0|publisher=[[Williams and Wilkins]]|edition=3rd|page=463}}</ref> The pink color of the esophageal mucosa contrasts to the deeper red of the [[gastric mucosa]],<ref name=KUO2006/><ref name=GD2002>{{cite book|editor1= Anthony DiMarino, Jr.|editor2=Stanley B. Benjamin|others=section editors Firas H. Al-Kawas|title=Gastrointestinal disease : an endoscopic approach|year=2002|publisher=Slack|location=Thorofare, NJ|isbn=978-1-55642-511-0|page=166|edition=2nd}}</ref> and the mucosal transition can be seen as an irregular zig-zag line, which is often called the z-line.<ref>{{cite book|editor1=Richard M. Gore|editor2=Marc S. Levine|title=High-yield imaging|date=2010|publisher=Saunders/Elsevier|location=Philadelphia|isbn=978-1-4557-1144-4|page=151|edition=1st}}</ref> Histological examination reveals abrupt transition between the [[stratified squamous epithelium]] of the esophagus and the [[simple columnar epithelium]] of the [[stomach]].<ref name="Moore-Agur">{{cite book|title=Essential Clinical Anatomy|url=https://archive.org/details/essentialclinica02edmoor|url-access=registration|edition=2nd|first1=Keith L|last1=Moore|first2=Anne M.R|last2=Agur|publisher=[[Lippincott Williams & Wilkins]]|year=2002|isbn=978-0-7817-2830-0|page=[https://archive.org/details/essentialclinica02edmoor/page/145 145]}}</ref> Normally, the [[stomach#Sections|cardia]] of the stomach is immediately distal to the z-line<ref>{{cite book|last=Barrett|first=Kim E.|title=Gastrointestinal physiology|year=2014|publisher=Mc Graw Hill.|location=New York|isbn=978-0-07-177401-7|pages=Chapter 7: "Esophageal Motility"|edition=2nd}}</ref> and the z-line coincides with the upper limit of the gastric folds of the cardia; however, when the anatomy of the mucosa is distorted in [[Barrett's esophagus]] the true gastroesophageal junction can be identified by the upper limit of the gastric folds rather than the mucosal transition.<ref>{{cite book|title=Specialist Training in Gastroenterology and Liver Disease|editor1-first=Richard G|editor1-last=Long|editor2-first=Brian B|editor2-last=Scott|isbn=978-0-7234-3252-4|publisher=Elsevier Mosby|year=2005|pages=25–26}}</ref> The functional location of the lower oesophageal sphincter is generally situated about {{convert|3|cm|in|abbr=on|frac=4}} below the z-line.<ref name=KUO2006>{{cite journal|last1=Kuo|first1=Braden|last2=Urma|first2=Daniela|url=http://www.nature.com/gimo/contents/pt1/full/gimo6.html|title=Esophagus – anatomy and development|journal=GI Motility Online|date=2006|doi=10.1038/gimo6|doi-broken-date=1 November 2024}}</ref>