The colon is a tube that is about 5 feet long and 2.5 inches in diameter, according to InnerBody. It is made up of four layers. The innermost layer of the colon is smooth and made up of epithelial tissue. It is called the mucosa, and as its name implies, it secretes mucous to protect and lubricate the colon as food passes through it.Continue Reading
The mucosa layer is surrounded by the submucosa, which is filled with nerves, connective tissue and blood vessels. It is surrounded by the muscularis layer, whose muscles help the colon contract and push food along, explains InnerBody. As it contracts, the muscles form pouches called haustra. The outermost layer of the colon is the serosa. It is simply a thin layer of epithelial tissue that secretes serous fluid, which keeps the outer wall of the colon lubricated and protected if it rubs against other internal structures in the body.
Inside the body, the colon is a squared-off U shape that encloses the much longer small intestine, notes InnerBody. The colon is connected to the small intestine on the right side of the abdomen. From this attachment, the colon extends down into the cecum and up into the ascending colon. It then bends about 90 degrees to form the transverse colon before bending another 90 degrees to form the descending colon. At this point, it becomes the S-shaped sigmoid colon that straightens into the rectum, which ends at the anus.Learn more about Conditions & Diseases