Expansion
A single end artery running in the mesoappendix from the ileocolic artery
Expansion
- Arises from the ileocolic artery, itself a branch of the superior mesenteric artery
- Runs behind the terminal ileum and then in the free edge of the mesoappendix
- Is a functional end artery with no significant collateral supply
The sequence of appendicitis follows from this. Luminal obstruction, by a faecolith, lymphoid hyperplasia or a tumour, causes continued mucus secretion, rising intraluminal pressure, then venous congestion and finally arterial compromise.
Because there is no alternative supply, ischaemia progresses to gangrene and perforation, typically within 24 to 72 hours. Bacterial invasion of the devitalised wall then produces peritonitis, localised by omentum into an appendix mass or abscess, or generalised.
At appendicectomy the artery is ligated in the mesoappendix before the base is divided.