30 



Rectum. 



359. Horizontal Section through the Pelvis 



tit the lower border of the third sacral vertebra. After removal of the 

 peritoneum the urinary bladder and collapsed rectum were turned for- 

 wards. After J. H e n 1 e. 



The longitudinal muscular fibres of the large intestine 

 are in the coecum and colon collected into three flat bands, the Fasciae, 

 TaeniaeValsalvaes. Liyanicnta coll (see Fig. 351); these are the Fascia omentalis, 

 mesenterica and libcra. In the sigmoid flexure and rectum they are spread 

 out into a uniform layer of longitudinal muscular fibres; the circular 

 fibres form at the end of the rectum the internal sphincter muscle, J\l. 

 xpliindcr am interims. The other muscles at the end of the rectum are 

 the 3T. sphincter am extcrnus and M. Inator ani ; the origin and connection 

 of the latter with the M. rccto-coccyyeus is evident from the figure. 



In the in u c o u s in c m b r a n e of the large intestine there 

 are certain permanent folds, Plicae slgmoideae (see Fig. 355), containing 

 circular fibres, the last of which lies about 3 inches above the anus; 

 this mucous membrane has no villi, but there are crypts of Lieber- 

 ktihn and solitary follicles. Towards the end of the rectum the 

 folds of the mucous membrane form the Sinus Morgayni. 



