1. The Appendix

2. 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.

3. 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

4. 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

5. 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