54 PROFESSOR A. BIRMINGHAM. 



Jonnesco, recognising that this portion of the intestine lies 

 partly in the iliac fossa and partly in the pelvis, very appro- 

 priately calls the former portion the iliac colon, and the latter 

 the pelvic colon. The iliac colon includes the portion of the 

 ' sigmoid flexure ' which extends from the crest of the ilium to 

 the inner side of the psoas muscle (that is, the brim of the 

 pelvis), and is usually destitute of a mesentery. The pelvic 

 colon embraces the remainder of the sigmoid colon and the 

 ' first part of the rectum,' both of which are attached by a 

 continuous mesentery, and form one large loop, lying as a rule in 

 the pelvic cavity, and ending about the level of the third sacral 

 vertebra by passing into the rectum proper, which is destitute 

 of a mesentery. The division is a natural one, for, as Jonnesco 

 points out, the pelvic colon forms a free loop with a long 

 mesentery, whilst the part that precedes it — the iliac colon — and 

 the part which succeeds it — the rectum — are fixed, and devoid 

 of a mesenteries. 



The pelvic colon, beginning at the inner edge of the psoas, 

 plunges over the brim into the pelvic cavity, on the floor of 

 which it runs, as a rule, to the right and backwards, resting on 

 the upper surface of the bladder ; having reached the back of 

 the pelvis it turns to the left towards the middle line, where it 

 bends down — forming a recto-colic flexure — and passes into the 

 rectum. 



The loop of the pelvic colon is subject to numerous and con- 

 siderable variations, which are chiefly dependent upon its length 

 and that of its mesentery, and the state of emptiness or disten- 

 sion of itself and the other pelvic viscera. When the intestine 

 is long, the loop is more complex ; when short, more simple. 

 When the bladder and rectum are distended, or when the 

 pelvic colon itself is much distended, it is unable to find 

 accommodation in the true pelvis, and consequently it turns up 

 into the abdominal cavity, almost any part of the lower half of 

 which it may occupy. But in the great majority of cases (92 

 per cent, according to Jonnesco) it is found after death lying 

 entirely within the pelvic cavity. 



As the tsenicC of the descending colon are followed down, it 

 will be found that the postero-external gradually passes on to 

 the front, and unites with the anterior taenia to form a broad 



