The appendix is a closed-ended, narrow, worm-like tube up to several inches in length that attaches to the cecum (the first part of the colon). (The anatomical name for the appendix, vermiform appendix, means worm-like appendage.) The inner lining of the appendix produces a small amount of mucus that flows through the open central core of the appendix and into the cecum. The wall of the appendix contains lymphatic tissue that is part of the immune system. Like the rest of the colon, the wall of the appendix also contains a layer of muscle, but the layer of muscle is poorly developed.
It is not clear if the appendix has an important role in the body in older children and adults. In young children it may have an immune function. There are no major, long-term health problems resulting from removing the appendix although a slight increase in some diseases has been noted, for example, Crohn’s disease.