THE ABDOMINAL CAVITY 307 



the left side of the vertebral column until the fingers are caught 

 in the loop of the flexure (see also p. 301). 



Duodenal Peritoneal Fossae. In the region of the duodeno-jejunal 

 flexure there are several inconstant fossae which require description, as they 

 may be responsible for strangulated retro-peritoneal hernias. 



1. The superior duodenal fossa is bounded in front by a free crescentic 

 margin, which extends to the left for about one inch from the duodeno-jejunal 

 flexure. Its mouth looks downwards, while its cavity passes upwards towards 

 the pancreas. The upper part of the inferior mesenteric vein may lie along 

 its lateral border and project into its anterior wall. 



2. The inferior duodenal fossa is at a lower level and its mouth looks 

 upwards. Its anterior margin is about one inch long and is attached medially 

 to the fourth part of the duodenum. 



3. The paraduodenal fossa, when present, is larger than the others. Its 

 mouth looks medially, and its free crescentic margin, which may be two inches 

 long, may unite the lateral extremities of the free borders of the superior and 

 inferior fossae when they are also present. The inferior mesenteric vein runs 

 upwards in its anterior wall, and the ascending branch of the left colic artery 

 (p. 340) may occupy a similar position or may lie along its lateral margin. 

 When a hernia enters this fossa it carries its sac downwards and laterally 

 behind the posterior parietal peritoneum and the vessels already mentioned, 

 but in front of the left ureter or kidney. Should strangulation occur, great 

 care must be taken in dividing the neck of the sac lest the inferior mesenteric 

 vein or the left colic artery be injured ; the neck of the sac should be incised 

 in a downward direction, parallel to the vessels. 



4. The retro-duodenal fossa lies behind the flexure on the anterior aspect 

 of the aorta and vertebral column. Its mouth looks towards the left, and 

 so when all four fossae are present their margins form a continuous circular 

 edge. 



Surface Marking of the Duodenum. The duodenum can now be 

 mapped out on the surface. The first flexure lies a little above the trans- 

 pyloric plane at a distance of 1^-2 inches from the middle line. The second 

 portion descends medial to the right lateral line and extends a little below 

 the subcostal plane. The third port-ion crosses the middle line horizontally, 

 and the fourth ascends to the duodeno-jejunal flexure, which just reaches 

 the transpyloric plane, one inch to the left of the middle line. 



The Liver occupies most of the right hypochondriac and 

 epigastric regions. It is roughly pyramidal in shape, its base 

 being directed to the right and its apex lying behind the fifth 

 left intercostal space, half an inch medial to the left lateral line. 



The Anterior Surface of the liver is related to both halves 

 of the diaphragm, and in the middle line it lies in direct contact 

 with the anterior abdominal wall, occupying the upper part of 

 the subcostal angle (Fig. 97). In this region it can readily be 

 examined by palpation and percussion. It is partially over- 

 lapped by the right lung and pleura and, under cover of the left 

 costal margin, by the left pleura and, to a slight extent, by the 

 pericardium (Fig. 97). Its upper border can be mapped out 

 by a line drawn from a point on the fifth right rib half an inch 

 medial to the right lateral line, to a second point in the fifth 



20 



