DIGESTIVE SYSTEM. 



verse colon in front of the duodenum. It lies on the Iliacus, 

 Quadratus lumborum, and lower and outer part of the right 

 kidney; peritoneum covers its front and sides. [1082] 



The transverse colon is nineteen or twenty inches long, runs 

 transversely to the left to the lower end of the spleen, and 

 there bends (splenic flexure) sharply downward to become the 

 descending colon. A triangular fold (phrenico-colic, or costo- 

 colic ligament, or sustentaculum lienis) runs from the splenic 

 flexure to the diaphragm opposite the eleventh rib. Perito- 

 neum covers it completely, except the back of the first few 

 inches. The meso-colon is short at its ends but long elsewhere 

 and allows this colon to hang down ; for this reason the left 

 end runs upward, backward, and to the left. This colon lies 

 below the liver, stomach, and pancreas (tail); behind the 

 omentum and (left end) stomach; and in front of the duo- 

 denum and pancreas (head). [1082] 



The descending colon is from four to six inches long and de- 

 scends to the iliac crest, where it becomes the iliac colon. 

 It lies external to the left kidney and upon the Diaphragm 

 and Quadratus lumborum. Peritoneum usually covers its 

 front and sides only. [1083] 



The iliac colon is five or six inches long and runs downward 

 and then inward upon the Ilio-psoas to the inner border of the 

 Psoas, where it becomes the pelvic colon. Peritoneum usually 

 covers its front and sides only. [1085] 



The pelvic colon is fifteen, or more, inches long and descends 

 into the pelvis, where it forms loops, and becomes the rectum 

 opposite the third sacral vertebra. It is completely covered 

 by peritoneum, has an extensive meso-colon, and is freely 

 movable. [1086] 



Rectum. This is dilated, five or six inches long, and de- 

 scends to the lower and back part of the prostate (one and a 

 half inches in front of but lower than the tip of the coccyx). 

 There, bending backward and downward around the ano- 

 coccygeal body (muscular and connective tissue), it pierces 



[221] 



