Figure 1 - Opposing sling and clasp muscle fibers. The longitudinal muscle layer of the stomach has been cut away to show the opposing sling and clasp muscle fibers.

These fibers sit in tonic opposition until a swallow triggers receptive relaxation. It is thought that progressive stretching of these fibers leads to valve incompetence and subsequent gastroesophageal reflux disease (GERD). Antireflux procedures restore the anatomic barrier by re-creating the one-way valve of the lower esophageal sphincter (LES). (Source: Jobe BA, et al. Endoscopic appraisal of the gastroesophageal valve after antireflux surgery. Am J Gastroenterol 2004;99(2):241 with permission from Blackwell Publishing.)