Unlike the mobile small bowel, most of the colon is relatively fixed in place. There is no mesentery along with the cecum or the ascending and descending colon, while the transverse colon is enclosed by a mesentery called the transverse mesocolon and is modestly mobile.

The ascending colon and descending colon both lie mesoperitoneally (covered by the peritoneum from three sides) in the lateral gutters of the abdominal cavity, while the transverse colon lies intraperitoneally. The cecum is also an intraperitoneal structure.

The splenic flexure is anchored by peritoneal folds, connecting it with the diaphragm and spleen. As the descending colon crosses the iliac crest, it becomes the sigmoid colon which is completely covered by the peritoneum and is relatively mobile due to its long mesenteric attachment (sigmoid mesocolon). The average length and diameter of the sigmoid colon varies, depending on the amount of indigestible fiber in the diet and other unknown factors.

The colon generally has a larger lumen than the small intestine, except the descending colon, which may be the same diameter when empty.

The cecum is the widest portion of the organ so that it is rarely obstructed by a tumor. Therefore, cecal malignancies often present as iron deficiency anemia secondary to occult bleeding from ulcerations on the tumor surface.

Three main features distinguish the colon:

Taenieae coli: three longitudinal muscle bands situated equidistantly around the circumference of the colon;
Haustra: sacculations seen in the colon wall that give the intestine its segmented appearance; the wall of the large intestine is formed into pocket-like sacs or small segmented pouches caused by sacculation; contractions of muscle fibers in the teniae provide this intestine segmentation and the teniae are shorter than the length of the intestine;
Appendices epiploicae (epiploic appendices or epiploic appendages): the visceral peritoneum contains tiny fat-filled droplets or pouches called the epiploic appendices, and they hang down mainly along the free and omental taeniae and are attached to them; these appendices can become inflamed - this condition is called epiploic appendagitis.

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Distinguishing features of the colon