372 CLINICAL APPLIED ANATOMY. 



the appendix behind and the ileo-ca3cal fold in front. Small 

 intestine may become entangled in this fossa, and the appendicular 

 artery then lies behind the mouth of the hernial sac. Hernia 

 into the retro-caecal fossa usually goes by the name of retro-colic, 

 since the sac lies behind the lower part of the ascending colon. 

 The outer boundary of the fossa is known as the retro-colic fold 

 or suspensory ligament of the caecum. The inner boundary is a 

 downward prolongation of the mesentery of the small intestine 

 towards the iliac fossa, which is sometimes called the inferior 

 ligament of the caecum, and may reach to the inguinal canal 

 or the broad ligament. 



Intersigmoid hernia lies in a pouch behind the root of the 

 mesentery of the pelvic colon. The common iliac artery and 

 the ureter lie behind the mouth of the fossa. 



Hernia into the foramen of Winslow has been met with. 

 Some part of the small intestine or colon passes through the 

 foramen into the lesser sac of the peritoneum, and is strangu- 

 lated. The stomach lies in front of the sac, and the presence of 

 the hepatic artery, portal vein, and bile duct in the constricting 

 ring may render relief of the condition impossible. 



Gross congenital malformations of the peritoneum are often 

 associated with the different forms of internal hernia. Indeed, 

 the occurrence of hernia into the foramen of Winslow is impos- 

 sible apart from such abnormalities. Either the caecum and 

 ascending colon fail to migrate in the usual manner towards the 

 right iliac fossa, or an abnormal length of mesentery, or a 

 mesentery common to great and small bowel is present. 



A volvulus or twist is only likely to occur in those parts 

 of the bowel which are provided with a long fan- shaped mesentery. 

 This condition is normally fulfilled by the pelvic colon and the 

 coils of small intestine, but as an abnormality the ascending 

 colon may have an unusually long mesocolon, or there may be 

 a common mesentery for the small intestine, caecum, and a 

 variable length of the colon. The pelvic colon is the part 

 usually twisted ; the mesentery is of the required shape, and 

 the bowel is constantly changing its position with the varying 



