THE ABDOMINAL CAVITY 333 



csecal vermiform process lies in contact with the fascia iliaca 

 and is only in contact with peritoneum at its base (Fig. 104, 5.) 



The course taken by an abscess in connection with a retro- 

 caecal vermiform process will depend on which of the three 

 varieties is present. In (a) the abscess forms in the lowest part 

 of the right para-colic gutter and reaches the anterior abdominal 

 wall close to the anterior superior iliac spine. It then gives 

 rise to a swelling, which is dull on percussion. Adhesions, 

 however,, may shut off the caeca! fossa so that the abscess, as 

 it enlarges, pushes the caecum forwards with the result that a 

 tympanitic note is obtained on percussion over the swelling. 



In (b) the abscess may rupture through the gut wall or it may 

 burst into the caecal fossa, in which event the condition is the 

 same as that described for (a). 



In (c) the abscess forms in the extra-peritoneal fat. The 

 caecum is thrust forwards against the anterior abdominal wall 

 so that a tympanitic note is obtained on percussion, and this 

 may be misleading, unless the possibility of an extra-peritoneal 

 abscess is kept in mind. Delay in recognising this condition 

 allows the pus to spread upwards behind the peritoneum until 

 it reaches the extra-peritoneal subphrenic danger zone. 



Such an abscess may be evacuated by the extra-peritoneal 

 route, but the access is rarely sufficient for removal of the 

 vermiform process, and, further, a wide extent of cellular tissue 

 is necessarily opened up. It is, therefore, better to empty it 

 through the peritoneal cavity. The area medial to the ascending 

 colon and caecum is packed off, and the floor of the right para-colic 

 gutter is incised. In this way the caecum is rendered movable 

 and can be retracted medially. The abscess can be evacuated 

 and the vermiform process removed through the extended 

 grid-iron incision (p. 248). 



(5) The infra-hepatic position is referred to on p. 346. 



The ileo-colic artery arises from the superior mesenteric 

 below the third part of the duodenum, and runs downwards 

 and to the right in front of the right ureter and psoas major 

 (Fig. 1 06). It breaks up near the ileo-colic fossa into branches 

 which supply (i) the terminal part of the ileum, (2) the ascending 

 colon, (3) the caecum, and (4) the vermiform process. The 

 caecal arteries, anterior and posterior, supply the anterior and 

 posterior surfaces of the caecum. The artery to the vermiform 

 process descends behind the ileum and enters the free border 

 of the mesentery of the vermiform process. It does not 



