998 



THE ORGANS OF DIGESTION. 



from its subhepatic position has never contracted extensive adhesions to the pos- 

 terior abdominal wall, and a fossa is left between the layers of its mesocolon. 



Anterior 

 vascular fold 



Non-vascular interme- 

 diate fold 



Posterior vascular fold 



FIG. 621. The three ileo-csecal folds of Ateles ater. (Huntington.) 



The ascending colon can be easily separated from its posterior connections. 



These fossae may nearly all be the site of retro-peritoneal hernias. Attention 



was first called to such hernias as early as 1778, and a most important work on 



Posterior vascular fold 

 ' (proximal part) 



/ Posterior vascular fold 

 'or mesenteriolum 



Non-vascular inter- 

 mediate fold 



lleo-cxcal fossa- -/'- 



Entrance of appendicu- 

 lar artery 



FIG. 622. Human caecum and ileo-colon, showing ileo-csecal fossa. (Huntington.') 



the subject appeared in 1857 by Treitz, who described the fossa of his name and 

 reported cases of " retro-peritoneal " hernia through his fossa. 



