What is the anatomy of the appendix?

Updated: Jul 23, 2018
  • Author: Sandy Craig, MD; Chief Editor: Barry E Brenner, MD, PhD, FACEP  more...
  • Print
Answer

The appendix is a wormlike extension of the cecum and, for this reason, has been called the vermiform appendix. The average length of the appendix is 8-10 cm (ranging from 2-20 cm). The appendix appears during the fifth month of gestation, and several lymphoid follicles are scattered in its mucosa. Such follicles increase in number when individuals are aged 8-20 years. A normal appendix is seen below.

Normal appendix; barium enema radiographic examina Normal appendix; barium enema radiographic examination. A complete contrast-filled appendix is observed (arrows), which effectively excludes the diagnosis of appendicitis.

The appendix is contained within the visceral peritoneum that forms the serosa, and its exterior layer is longitudinal and derived from the taenia coli; the deeper, interior muscle layer is circular. Beneath these layers lies the submucosal layer, which contains lymphoepithelial tissue. The mucosa consists of columnar epithelium with few glandular elements and neuroendocrine argentaffin cells.

Taenia coli converge on the posteromedial area of the cecum, which is the site of the appendiceal base. The appendix runs into a serosal sheet of the peritoneum called the mesoappendix, within which courses the appendicular artery, which is derived from the ileocolic artery. Sometimes, an accessory appendicular artery (deriving from the posterior cecal artery) may be found.


Did this answer your question?
Additional feedback? (Optional)
Thank you for your feedback!