The Appendix

Definition Is a vestigeal organ, a tubular structure of about 5 cm with a lumen It is attached to the caecum Situation In the right iliac fossa McBurney’s point corresponds to the base of appendix – a point which is the junction of lateral 1/3 and medial 2/3 of a line which is drawn from the umbilicus to the anterior superior iliac spine.

Features of the appendix Found at the point where the three taeniae coli converge on the postero medial wall of the caecum It opens into the caecum at one end and the other end is blind The taeniae coli merge into a complete longitudinal muscle layer over the appendix Mesoappendix : a peritoneal fold enclosing the appendicular vessels. It is a prologation of the mesentery of the terminal ileum. It contains the appendicular artery – a branch of the posterior caecal artery The tip of the appendix lies at the level of the brim of the pelvis The position of the appedix in relation to the caecum and terminal ileum is variable

Structure Varies considerably in length and circumference The lumen is narrow may admit a match stick Peritoneal layer – adventitia Muscular coat Longitudinal and circular (outer and inner layers) muscle layer Submucosa Has a well developed submucous coat containing lymphoid follicles The lumen has longitudinal folds of mucous membrane

Blood supply Appendicular artery a branch of ileo- colic artery Appendicular vein drains into ileo-colic vein  portal vein Lymphatic drainage Into ileo-caecal lymph nodes