Layers of the Gastrointestinal Tract

The gastrointestinal tract shares four concentric layers from esophagus to rectum: innermost mucosa with epithelium, lamina propria, muscularis mucosae; submucosa dense connective with glands, vessels, Meissner plexus; muscularis propria inner circular outer longitudinal smooth muscle plus Auerbach plexus for motility, skeletal in upper esophagus and external anal; adventitia or serosa outermost, retroperitoneal parts adventitia, intraperitoneal serosa with mesentery. Variations adapt function regionally.