416 ABDOMEN 



wall of the pelvis, displacing the soft fat, until he touches the 

 ureter. The region which he will thus investigate is the lower 

 and anterior part of a large area, known as the cave of Retzius, 

 in which the extraperitoneal fat has very slight attachment 

 either to the peritoneum or to the pelvic fascia, and in which, 

 therefore, it is very easily displaced. The area extends from 

 the hypogastric artery of one side round the front of the bladder 

 to the hypogastric artery of the opposite side, downwards to the 

 visceral layer of the pelvic fascia, and upwards, between the 

 umbilical (O.T. obliterated hypogastric) arteries, to the um- 

 bilicus. The facility with which he displaces the fatty tissue 

 should demonstrate to the dissector how easy, in that area, will 

 be the spread of urine effused from a ruptured bladder, or of blood 

 running from a divided artery, or of effusions due to inflammatory 

 conditions. 



The dissector must now remove the extraperitoneal fat 

 first from the ductus deferens, then from the region of the 

 ureter, and afterwards from the hypogastric vessels and their 

 branches and tributaries. Whilst that is being done, the ob- 

 turator nerve will be brought into view to the lateral side of the 

 ureter, and below the level of the umbilical artery. Whilst 

 removing the fat and displaying the structures embedded in its 

 substance, the dissector must be careful not to injure either the 

 parietal or the visceral pelvic fascia. He will find that some of 

 the branches of the hypogastric artery pierce the parietal fascia 

 as they leave the pelvis, and that the visceral branches, the 

 rectum, the ureter, and the ductus deferens, pass into the sub- 

 stance of the visceral layer. 



When the dissection is completed the student should note 

 the relative positions of the structures he has exposed. The 

 ductus deferens will be seen passing downwards and backwards, 

 on the side wall of the pelvis, till it meets the ureter, 

 which is passing downwards, from the junction of the 

 lateral and posterior walls of the cavity and along the front 

 of the hypogastric artery. Before they meet, both the ductus 

 deferens and the ureter turn medially and, medial to the point 

 of crossing, they both enter the visceral layer of the pelvic 

 fascia. Behind the ureter is the hypogastric artery, dividing 

 into its anterior and posterior divisions. Running forwards 

 on the lateral side of the ureter and the ductus deferens 

 are the umbilical, the obturator, the middle and inferior 

 vesical, and, not uncommonly, the middle haemorrhoidal 

 branches of the anterior division of the hypogastric artery. 

 Springing from the umbilical artery are one or more superior 

 vesical arteries, whilst below the umbilical artery and above 

 the obturator artery is the obturator nerve, which pierces 

 the parietal fascia at the back of the pelvis and runs 

 forwards, above the corresponding artery and vein, to the 



