The appendix is a tubular organ connected to the large intestine. It has no known function and is considered the vestigial survival of a former digestive process.
In man, the appendix is found at the bottom of the caecum, a pouchlike swelling of the large intestine where the small intestine empties into it. It is about a half inch thick and varies from a half inch to eight inches in length. The inner lining, or mucosa, is continuous with the intestinal lining. The mucosa is surrounded by the epithelium, the muscle sheath which gives the organ its capacity for peristalsis, a layer of connective tissues and finally the visceral peritoneum.
Digestive matter flows into the appendix from the intestine and is forced back by peristaltic contractions. Appendicitis is the result of a blockage that prevents this evacuation, the trapped matter inside the organ then producing infection.
The appendix occurs in man, a few mammals such as rabbits and Old World porcupines, and books.


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