Figure 6a (below). The SMALL INTESTINE (a) is located in the lower portions of the abdomen, inferior to the liver (l) and stomach (s), and partially framed by the large intestine (asterisk). Its wall has all four basic layers of the alimentary canal. The MUCOSA (b) of an epithelium and lamina propria, the SUBMUCOSA (c) of connective tissue, the MUSCULARIS (d) of an inner circular (thicker in this micrograph) and outer longitudinal layers of smooth muscle, and finally the SEROSA (e) of a simple squamous epithelium (barely evident on this image).