Appendix, in anatomy, is a structure attached to a larger or more important part. The term usually refers to the vermiform (wormlike) appendix, a slender, closed tube that extends from the cecum, the first part of the large intestine. The vermiform appendix lies in the lower right part of the abdomen in human beings. It is also found in the higher apes, some rodents, and various other animals. Rats and certain other rodents have a long appendix that functions in digestion. In human beings, it probably has no function. Some people believe that the appendix lost its function through evolution. When inflamed, it causes a disease known as appendicitis. See also Appendicitis.