1184 



SPLANCHNOLOGY 





point of view, in connection with the removal of the lower part of the rectum. It 

 is higher in the male than in the female. In the former the height of the recto- 

 vesical excavation is about 7.5 cm., i. e., the height to which an ordinary index 

 finger can reach from the anus. In the female the height of the rectouterine 

 excavation is about 5.5 cm. from the anal orifice. The rectum is surrounded by 



a dense tube of fascia derived from the 

 fascia endopelvina, but fused behind 

 with the fascia covering the sacrum 

 and coccyx. The facial tube is loosely 

 attached to the rectal wall bv areolar 



tissue in order to allow of distension of 

 the viscus. 



Relations of the Rectum. The upper part 

 of the rectum is in relation, behind, with the 

 superior hemorrhoidal vessels, the left Piri- 

 formis, and left sacral plexus of nerves, which 

 separate it from the pelvic surfaces of the 

 sacral vertebrae; in its lower part it lies directly 

 on the sacrum, coccyx, and Levatores ani, a 

 dense fascia alone intervening; in front, it is 

 separated above, in the male, from the fundus 

 of the bladder; in the female, from the intes- 

 tinal surface of the uterus and its appendages, 

 by some convolutions of the small intestine, 

 and frequently by the sigmoid colon ; below, it 

 is in relation in the male wi th the triangular 

 portion of the fundus of the bladder, the vesic- 

 ulae seminales, and ductus deferentes, and 

 more anteriorly with the posterior surface of 

 the prostate;, in the female, with the poste- 

 rior wall of the vagina. 



The Anal Canal (pars analis recti) (Figs. 1079, 1080, 1081), or terminal portion of the 

 large intestine, begins at the level of the apex of the prostate, is directed downward 

 and backward, and ends at the anus. It forms an angle with the lower part of 





FIG. 1079. Coronal section through the anal canal. 

 (Symington.) B. Cavity of urinary bladder. V.D. Ductus 

 deferens. S.V. Seminal vesicle. R. Second part of 

 rectum. A.C. Anal canal. L.A. Levator am. I.S. 

 Sphincter ani internus. E.S. Sphincter ani externua. 



LONGITUDINAL 



MUSCLE FIBRES 



OF RECTUM 



PART OF 



LCVATOR ANI 



INTERNAL 



SPHINCTER 



ANAL CANAL 



RUG/E OF 

 MUCOUS 

 MEMBRANE 



COLUMNS OF 

 MORGAGNI 



ANAL VALVES 



FIG. 1080. The interior of the anal canal and lower part of the rectum, showing the columns of Morgagni and the anal 

 valves between their lower ends. The columns were more numerous in the specimen than usual. (Cunningham.) 



the rectum, and measures from 2.5 to 4 cm. in length. It has no peritoneal cov- 

 ering, but is invested by the Sphincter ani internus, supported by the Levatores 

 ani, and surrounded at its termination by the Sphincter ani externus. In the 



