The gastric mucosa is the inner layer of the stomach wall. It is formed by a surface epithelium, lamina propria, and muscularis mucosa. The surface epithelium of the stomach is the simple columnar epithelium. The lamina propria consists of connective tissue, blood vessels, and lymphatics. Below the lamina propria lies the muscle layer or muscularis mucosa containing smooth muscle fibers. The thinnest mucosa lines the cardiac part of the stomach.