食管:抗GER屏障 食管下括约肌( Lower esophageal sphincter,LES) Specialized smooth muscle of Crus of esophagus diaphragm Intraabdominal esophagus食管：抗GER 屏障 n 食管下括约肌（Lower esophageal sphincter , LES) Specialized smooth muscle of C esophagus rus of diaphragm Intraabdominal esophagus