THE LARGE INTESTINE 191 



Posteriorly. Right kidney, 2nd part of duodenum, transverse 

 meso-colon, pancreas, and small intestines. 



The descending colon passes from the end ot the transverse 

 colon by a bend, the splenic flexure. Between the splenic 

 flexure and the diaphragm, opposite the roth left rib, is a fold 

 of the peritoneum, the costo-colic ligament, which slings up the 

 spleen. The gut then passes downwards to the left iliac crest, 

 ending in the iliac colon. The peritoneum invests its anterior 

 and lateral surfaces. Length, 4 to 6 inches. 



Relations. Behind. Left kidney, quadratus lumborum, and 

 psoas. 



In front. Small intestine. 



Inner side. Outer border of left kidney. 



The iliac colon is continuous with the descending colon at 

 the left iliac crest, and ends at the inner border of the left psoas. 



Peritoneum invests its anterior and lateral surfaces ; it has 

 no mesentery. 



Relations. In front. Small intestines; when distended, the 

 anterior abdominal wall. Behind. Left ilio-psoas. 



Length. 5 to 6 inches. 



The pelvic colon extends from the inner border of the 

 psoas to the level of the 3rd sacral vertebra. 



Length. 16 or 17 inches ; very variable. It has an extensive 

 mesentery. 



Relations. Passing over left brim of pelvis, it crosses left 

 external iliac vessels and left ureter, and passes to right 

 margin of pelvis, resting on bladder in male and uterus in 

 female ; above lie coils of small intestine. It then turns back 

 to mid-line on posterior wall of pelvis, and, forming a second 

 bend, descends to end in the rectum. 



The rectum : 



Extent. From the 3rd sacral vertebra to the tip of the 

 coccyx (5 to 6 inches long). 



Relations. It has peritoneum on the upper of anterior 

 surface only, and no mesentery. 



In front. Recto-vesical pouch : triangular area at base of 

 bladder, vesiculaeseminales, vasa deferentia, posterior surface 

 of prostate (male), posterior wall of vagina (female). 



Behind. Sacrum, coccyx, levatores ani. 



Laterally. Pararectal fossa, below coccygeus. 



The anal canal : 



Extent. From the tip of the coccyx to anus (i to i inches 

 Jong). 



Direction. Downwards and backwards. 



Relations : 



In front. Membranous part of the urethra, bulb of corpus 



