The Appendix: Anatomy, Location, Function, and Appendicitis

The vermiform appendix is a blind-ended, finger-like pouch arising from the posteromedial cecum, typically at the confluence of the taeniae coli.

Location

• Right lower quadrant (RLQ), McBurney's point (2/3 from umbilicus to ASIS)
• Retrocecal (65%), pelvic (30%), pre-/post-ileal, subcecal variants
• Length: 2–20 cm (avg 8–10 cm)

Histology & Immunologic Function

• Rich in lymphoid tissue (GALT: gut-associated lymphoid tissue)
• B-cell maturation, IgA production
• Maintains commensal microbiome reservoir ("safe house" hypothesis)
• Innate immune sensing

Clinical Significance

• Appendicitis: Obstruction → inflammation → perforation risk. RLQ pain, fever, leukocytosis. Surgical emergency (appendectomy).
• Not essential: Removal has no major long-term sequelae; possible slight increase in Crohn's risk, C. difficile recurrence.