1420 



SUKFACE AND SUEGICAL ANATOMY. 



fossa look upwards. This is one of the situations at which an internal hernia 

 sometimes develops, the sac, as it enlarges, extending further and further into the 

 extra-peritoneal tissue on the posterior abdominal wall. Should strangulation 

 occur, the inferior edge of the orifice must be divided in a downward direction, in 

 order to avoid the inferior mesenteric vein which curves round the anterior and 

 superior aspects of the orifice (Treves). 



Jejunum and Ileum. To expose the coils of the jejunum and ileum completely, 

 the greater omentum, along with the transverse colon and the greater curvature 

 of the stomach, must be turned upwards. On account of the oblique attachment 

 of the mesentery, the greater number of the coils lie in the left infra-colic peritoneal 

 compartment, where they extend upwards to the left of the vertebral column as 

 far as the attachment of the transverse mesocolon and the inferior surface of the 

 pancreas ; here they lie in front of the inferior pole of the left kidney, in the angle 

 of the left colic flexure. 



The only certain means which the surgeon has of distinguishing the superior 

 from the inferior coils of small intestine is by their relation to the duodeno- 

 jejunal flexure and the ileo-caecal junction. Occasionally the plicae circulares 



VERMIEORM 

 PROCESS 



FIG. 1104. THE C^CAL FOLDS AND FOSS.E, 



In A, the caecum is viewed from the front ; the mesentery of the vermiform process is distinct, and is attached 

 above to the inferior surface of the portion of the mesentery going to the end of the ileum. In B, the 

 caecum is turned upwards to show a retro-caecal fossa, which lies behind it, and the beginning of the 

 ascending colon (from Birmingham). 



and the aggregated lymph nodules can be seen from the peritoneal aspect and 

 the jejunum and ileum thereby respectively identified. The terminal portion 

 of the ileum, which is attached by the inferior end of the mesentery to the 

 superior part of the right wall of the pelvis major, crosses the superior 

 aperture of the pelvis minor, and ascends along the medial edge of the caecum 

 before opening into it. The terminal loop of the ileum may be hooked up by passing 

 the finger along the medial side of the caecum downwards over the medial border 

 of the psoas major and the external iliac vessels into the pelvis minor. 



Meckel's diverticulum, which is due to persistent patency of the proximal portion of 

 the vitelline duct, is situated usually from two to three feet above the valve of the colon ; 

 its average length is two inches. Springing from the anti-mesenteric border of the ileum, 

 its termination is usually free, but it may be adherent either to the anterior abdominal 

 wall, to the mesentery, or, more rarely, to one of the adjacent viscera. When its termina- 

 tion is fixed it may give rise to strangulation of the intestine. 



Caecum. The caecum occupies the right iliac region and extends from the 

 anterior superior spine of the ilium to the superior aperture of the pelvis minor. 

 When empty, it is generally more or less completely overlapped by small intestine, and 

 frequently also by the greater omentum. When partly distended, the caecum comes 



