THE ABDOMINAL VISCEEA. 1423 



Descending Colon. The descending colon, like the ascending, is deeply placed 

 in the lumbar region and is related to the inferior half of the lateral border of the 

 left kidney. It is less frequently provided with a mesentery than is the ascending 

 colon. 



Iliac Colon. The iliac colon commences at the junction of the posterior and 

 middle thirds of the iliac crest, and ends at the superior aperture of the pelvis 

 minor by joining the pelvic colon. It possesses no mesentery 'and is connected to 

 the fascia covering the iliacus and psoas major muscles by loose areolar tissue. 

 Towards its termination it turns medially immediately above and parallel to the 

 inguinal ligament, and at its junction with the pelvic colon it lies in front of the 

 external iliac artery. Although, as a rule, it is entirely overlapped by coils of 

 small intestine, it can frequently be felt by firm palpation at the lateral part of the 

 left iliac fossa, because its muscular wall is comparatively thick and generally 

 contracted. 



Pelvic Colon. The pelvic colon, in consequence of possessing a well-developed 

 mesentery, forms a freely movable loop which, though usually confined to the 

 pelvis minor, may, when distended, rise well up into the abdomen. It is this 

 section of the large intestine which is opened for the purpose of making an 

 artificial anus in malignant disease of the rectum. 



The pelvic colon varies considerably in length, the average being sixteen or 

 seventeen inches. It is relatively longer and of greater calibre in the child than 

 in the adult. It is the part of the large intestine especially involved in the 

 condition known as megalocolon or Hirschsprung's disease a congenital abnormality 

 in which the large intestine is greatly dilated and hypertrophied. 



When the pelvic colon is thrown upwards and to the right so as to spread out 

 its mesentery, the latter is seen to be attached in an inverted V-shaped manner to 

 the posterior wall of the pelvis. At the apex of the V is a small peritoneal pouch 

 the inter-sigmoid fossa, situated just in front of the ureter as it crosses the 

 termination of the common iliac artery to enter the pelvis minor. This fossa is 

 one of the situations at which an internal retro-peritoneal hernia may originate. 

 The mouth of the fossa looks downwards and to the left, while above and to its 

 right is the sigrnoid artery. The fossa affords a guide to the commencement of the 

 pelvic portion of the left ureter. On account of the V-shaped attachment of this 

 mesentery it is convenient to speak of the pelvic colon as possessing an ascending 

 or proximal and a descending or distal limb. At the junction of the proximal 

 limb with the termination of the iliac colon is a more or less well-marked flexure 

 (the "last kink" of Arbuthnot Lane). It is to the proximal limb of the pelvic 

 colon that the divided inferior end of the ileum is anastomosed in the short-circuiting 

 operation of ileo-sigmoidostomy. 



In the author's operation of transplanting the ureters into the large intestine 

 for incontinence of urine, the result of epispadias in the female, and of ectopia 

 vesicse in either fcex, the left ureter is implanted into the ascending limb of the 

 pelvic colon and the right ureter into its descending limb. 



By dividing the attachment of the mesentery of the pelvic colon in the 

 operation of excision of the rectum, the pelvic colon may be mobilised sufficiently 

 to allow of its being brought down and sutured to the skin in the sacral region or 

 even to the anal region. Further, the mobility of the pelvic colon is such that 

 after resection of the descending and iliac colon and mobilisation of the left colic 

 flexure, the divided ends of the bowel can be sutured together without undue 

 traction. 



After operations on the female genital organs by the abdominal route for 

 example, after abdominal hysterectomy the surgeon makes use of the pelvic 

 colon and its mesentery by spreading them out over the pelvis so as to roof it in, 

 and so prevent any of the coils of small intestine from becoming adherent in the 

 pelvis. 



Kidneys. The kidneys lie behind the peritoneum, and extend higher up than 

 is often supposed, and laterally they do not extend so far away from the vertebral 

 column as is almost invariably depicted ; hence it is that, unless enlarged, the kidneys 

 can seldom be felt through the abdominal wall. The right kidney as a rule lies a 



