© 2013 Springer-Verlag Berlin Heidelberg. All rights are reserved. The esophagogastric junction is approximately 4 cm long with the proximal 2 cm positioned at the level of the esophageal hiatus of the diaphragm. The remaining junction lies below the diaphragm in the abdominal cavity, referred to as the submerged component (Wolf 1970). The lower esophageal sphincter (LES) complex is composed of the intrinsic distal esophageal smooth muscle thickening, what most people think of as the sphincter. The complex also includes the gastric sling fibers and the extrinsic sphincter formed by the crural diaphragm (Mittal and Balaban 1997). The internal and external sphincter components are anchored to one another by the phrenoesophageal ligament, forming the angle of His between the esophagus and the gastric fundus (Kahrilas 1999).