1268 



THE ORGANS OF DIGESTION 



behind the cecum, which has to be raised to bring the fossa into view. It varies 

 much in size and extent. In some cases it is sufficiently large to admit the index 

 finger and extends upward behind the ascending colon in the direction of the kidney; 

 in others it is merely a shallow depression. It is bounded and formed by two folds : 

 one, the external parietocolic fold, or the superior cecal fold, which is attached by 

 one edge to the abdominal wall from the lower border of the kidney to the iliac 

 fossa and by the other to the postero-external aspect of the colon; and the other, 

 the inferior cecal or mesentericoparietal fold, which is in reality the insertion of the 

 mesentery into the iliac fossa. In some instances the subcecal fossa is double. 



ILEO-APPENDICULAR 



SUPERIOR 

 CECAL FOLD 



ILEO-APPENDICULAR 

 FOSSA 



MESO-APPENDIX 



INFERIOR 

 CECAL FOLD 



FETROCECAt 

 FOSSA 



FIG. 992. The retrocecal fossa. The ileum and cecum are drawn backward and upward. ' (Souligoux.) 



3. The intersigmoid fossa (recessus inter sigmoideus) is constant in the fetus 

 and common during infancy, but disappears in a large percentage of cases as age 

 advances. Upon drawing the sigmoid flexure upward, the left surface of the sig- 

 moid mesocolon is exposed, and on it will be seen a funnel-shaped recess of the 

 peritoneum, lying on the external iliac vessels, in the interspace between the 

 Psoas and Iliacus muscles. This is the orifice leading to the fossa intersigmoidea, 

 which lies behind the sigmoid mesocolon, and in front of the parietal peritoneum. 

 The fossa varies in size; in some instances it is a mere dimple, whereas in others 

 it will admit the whole of the index finger. 



Any of these fossae may be the site of a retro peritoneal hernia. The pericecal 

 fossa? are of especial interest, because hernia of the vermiform appendix frequently 

 takes place into one of them, and may there become strangulated. The presence 

 of these pouches also explains the course which pus has been known to take in 

 cases of perforation of the appendix, where it travels upward behind the ascending 

 colon as far as the Diaphragm. 1 



Applied Anatomy. Study of the peritoneum by Robinson and others shows that absorption 

 takes place more rapidly from the region of the Diaphragm, less rapidly but still very actively from 

 the region of the small intestine, slowly from the pelvic region. Clinically we know that pelvic 





1 On the anatomy of these fossa?, see the Arris and Gale Lectures by Moynihan, 1899. 



