The appendix is located at the beginning of the large intestine again and has the shape of a “cul-de-sac”. Its medical term is caecum or cecum. The appendix is best known for appendicitis.
What is the appendix?
Infographic showing the anatomy and location of appendicitis. Click image to enlarge. The first section of the large intestine, located anterior to the right iliac crest, is less known by its medical name, “caecum,” than by the more common term appendix. This name comes from the fact that the large intestine ends “blindly” (from Latin: caecus = blind) at this point, i.e. it simply ends after about 6-8 cm in one direction. With a width of about 7cm, the appendix, as the widest section of the entire colon, is thus a kind of antechamber for the directly adjacent ascending part of the colon, the ascending colon.
Anatomy and structure
On the left side, the small intestine passes through the ileocecal valve (also called the “Bauhin valve”) into the appendix, which can also be seen in the form of a small protuberance. The lower end, strictly speaking the beginning of the colon, can be located externally by drawing an imaginary line between the navel and the anterior right end of the iliac crest. Approximately in the middle of this line is the “McBurney point” where the appendix vermiformis leaves the appendix. This is often mistakenly referred to as the appendix, and inflammation of the appendix (appendicitis) is not, strictly speaking, true “appendicitis.” The appendix contains a lot of lymphatic tissue in its wall structure and therefore plays an important role for the immune system against antigens that are absorbed via the digestive tract. It is supplied mainly by the caecal artery anterior (anterior appendiceal artery) and the caecal artery posterior (posterior appendiceal artery), which come from the ileocolic artery. Like the rest of the large intestine, the appendix, unlike the small intestine, has no villi. The increase in surface area that is so important for intestinal activity takes place here, as in the entire large intestine, through so-called crypts and haustra, which are formed by wrinkling of the lining of the large intestine.
Functions and tasks
Evolutionarily, the appendix played an essential role in digesting fiber-rich food components in humans in the past and still does in herbivores. However, human diet has changed a lot, we not only eat more meat today, but we also prepare food much more digestible and easier to digest. Thus, the appendix is only rudimentary or no longer present in humans and pure carnivores, while in herbivores it is even partially longer pronounced than in humans. In addition, the appendix serves as a reservoir for bacterial colonization of the large intestine. It also fulfills an important function by supporting the intestinal flora and its symbiotic bacteria in “times of crisis”:
In severe diarrheal diseases, in which the entire intestinal flora is often destroyed, these bacteria can survive in the appendix. They are thus available again to colonize the intestinal flora after the disease has been overcome.
Diseases, complaints and disorders
In addition to diseases that can affect the entire colon and thus also the appendix (e.g., ulcerative colitis, Crohn’s disease, colon cancer), there is actually only one known disease that is limited to the appendix alone: appendicitis, which is the inflammation of the appendix’s vermiform appendix. It occurs most often in children and adolescents. However, actual appendicitis (typhlitis) only exists when parts of the appendix beyond the appendix are affected by the inflammation. The most frequent causes of appendicitis are infections with pathogens or obstruction by faecaliths or other foreign bodies (e.g. cherry stones). In the diagnosis, one pays particular attention to severe pain around the navel and in the stomach area. Here, the McBurney point, where the patient is particularly sensitive to pain in the case of appendicitis, comes into play again as an important point during palpation (palpation). In the course of time, appendicitis can lead from mild irritation to severe inflammation to wall perforation (perforation into the free abdominal cavity) and thus to peritonitis, which, if left untreated, can become life-threatening.Nowadays, an inflamed appendix is removed relatively unspectacularly with the help of laparoscopic surgical methods, so that the patient is usually fit and ready for action again after a few days.
