Appendix
Definition
o Is a vestigeal organ, a tubular structure of about 5 cm with a lumen
o It is attached to the caecum
Situation
o In the right iliac fossa
o 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
o Found at the point where the three taeniae coli converge on the postero medial wall of the caecum
o It opens into the caecum at one end and the other end is blind
o The taeniae coli merge into a complete longitudinal muscle layer over the appendix
o Mesoappendix : a peritoneal fold enclosing the appendicular vessels.
o It is a prologation of the mesentery of the terminal ileum.
o It contains the appendicular artery - a branch of the posterior caecal artery
o The tip of the appendix lies at the level of the brim of the pelvis
o The position of the appedix in relation to the caecum and terminal ileum is variable
Structure
o Varies considerably in length and circumference
o The lumen is narrow may admit a match stick
o Peritoneal layer - adventitia
o Muscular coat
o Longitudinal and circular (outer and inner layers) muscle layer
o Submucosa
o Has a well developed submucous coat containing lymphoid follicles
o The lumen has longitudinal folds of mucous membrane
Blood supply
o Appendicular artery a branch of ileo- colic artery
o Appendicular vein drains into ileo-colic vein portal vein
Lymphatic drainage
o Into ileo-caecal lymph nodes
