Taenia coli mm.

The taeniae coli are three separate longitudinal ribbons of smooth muscle on the outside of the ascending, transverse, descending and sigmoid colons. They are visible, and can be seen just below the serosa. They are the Mesocolic, Free and Omental Coli. The teniae coli contract lengthwise to produce the haustra, the bulges in the colon.

The bands converge at the root of the vermiform appendix. At the rectosigmoid junction, the taeniae spread out and unite to form longitudinal muscle layer.

These bands correspond to the outer layer of the muscularis externa, in other portions of the digestive tract.