328 The Large Intestine 



The ileo-ccccal valve is the chink by which the small intestine opens 

 into the large. Its lips are so joined that, the fuller the blind end of 

 the rolon becomes, the tighter they are approximated and the less 

 the chance of fluid passing back between them into the small intestine. 

 In faecal vomiting the contents of the large intestine do not regurgitate 

 through the valve, and in the treatment of intestinal obstruction by in- 

 flation of the bowel the air does not pass through the valve. 



Serous coat of large intestine. The caecum is entirely sur- 

 rounded by peritoneum ; 1 it is not, as it was formerly thought to be, 

 attached to the iliac fossa by a meso-ca:cum. 



The ascending and the descending colon are completely invested 

 except on that aspect which lies against the quadratus lumborum, 

 whilst the transverse colon is covered on all aspects except where the 

 arteries enter. The sigmoid flexure, like the transverse colon itself, 

 is surrounded by a mesentery, and by this it hangs into the true pelvis. 

 The peritoneum entirely covers the first part of the rectum except 

 a strip on the sacral aspect ; the beginning of the second part is 

 covered only on the anterior and antero-lateral aspects, whilst the 

 rest of the second part and the whole of the third part is destitute 

 of serous covering. The fuller the colon becomes, the wider is the 

 surface devoid of peritoneum, and, conversely, the more empty it is, 

 the more complete is its mesentery 7 . 



I have operated in a case of strangulated caecal hernia in which, 

 though the bowel had a complete sac, I was unable to pass the 

 finger round it, as one could have done, had an ordinary pie,ce of bowel 

 been down. The caecum was attached to the back of the sac. It is 

 said that the caecum can descend along the inguinal canal behind the 

 peritoneum, taking no peritoneum with it for its sac such a hernia 

 must, indeed, be rare. 



The appendices epiploicse are small tassels of peritoneum and 

 fat which are attached to the large intestine ; being only upon the 

 intra-peritoneal surface of the bowel, they can give no help to the 

 surgeon who is seeking for the colon through the loin, unless he be there 

 performing a transperitoneal operation. 



The longitudinal muscular fibres are chiefly collected in three con- 

 spicuous bands, commencing at the vermiform appendix, and ceasing 

 at the end of the sigmoid flexure. When the large bowel is much dis- 

 tended the bands are less noticeable, but ordinarily they serve, as do 

 the appendices epiploicae, to distinguish the large from the small 

 intestine when the peritoneum is opened. The sacculation of the 

 colon is due to the comparative shortness of these bands. On account 

 of the difference in size and shape the percussion-note of the trans- 

 verse colon is of a higher pitch than that of the stomach. 



The longitudinal bands are conspicuous only where the colon is 

 covered by peritoneum ; it is useless, therefore, to look for them as a 



1 See Treves, I/ttntcrian Lectures, 1885. 





