Lower Esophageal Sphincter: a 2-4cm high pressure zone above the GE junction that prvents reflux and is more a physiologic rather than anatomic sphincter. Not evident radiographically but but manometry.
Z-Line: irregular serrated line that demarkates the squamocolumnar junction
- A Ring - broad smooth muscular ring (LES)
- B Ring - mucosal ring at Z-line, constant, smooth, symetric, if located 2 cm above diaphagmatic hitaus suggestive of hernia. Fixed membranous ring less than 13 mm passage is Schatzki's ring.
- C Ring - oblique sling fibers of stomach
Esophageal Hiatus - angled opening in the diaphragm, mobile, may be 1cm above diaphragm with swallowing