Appendix

The appendix, in biological terms, is a narrow, blind-ended tube attached to the cecum, part of the large intestine. The word appendix is also used for supplementary material added to a document, such as tables, figures, or extended methods.

In humans, the vermiform appendix is typically about 3 to 5 cm long, though lengths from 2 to 20 cm have been reported. Its position varies, but it is usually located in the lower right abdomen. The wall contains mucosa with lymphoid tissue and is part of the gut-associated lymphoid tissue. The exact function remains uncertain; proposed roles include participation in immune function during early life and acting as a reservoir for beneficial gut bacteria. In many herbivorous and omnivorous animals, related structures have fermentation functions; in humans the organ is largely vestigial.

Medical significance: Inflammation of the appendix, appendicitis, is a common acute condition requiring urgent care. Symptoms often begin as periumbilical pain that migrates to the right lower quadrant, with nausea, fever, and an elevated white blood cell count. Diagnosis is clinical but supported by imaging. Treatment is usually surgical removal, known as appendectomy, though in selected stable cases antibiotic therapy alone may be considered. Complications include perforation and peritonitis.

In literature and documentation, an appendix is material added at the end of a work to provide supplementary information such as data, methods, or additional figures. The term derives from Latin appendix, meaning “that which is added.”