THE BLADDER. 229 



iliac has, in front, the peritoneum and ureter (rectum on 

 left side) ; externally, the psoas muscle, and obturator 

 nerve ; behind, the internal iliac vein, lumbo-sacral nerve, 

 and pyriformis muscle ; on the right side the vein is 

 more external. 



Ligature of Internal Iliac Artery. This vessel is 

 reached by the same incision as that for the common 

 iliac, and the bifurcation being found, the space is very 

 limited upon which the ligature can be placed ; the 

 short thick trunk passes downwards and backwards 

 as far as the upper border of the great sacro-sciatic 

 notch. 



The external iliac vein lies just in the bifurcation of 

 the common into external and internal iliac, and is liable 

 to be in the way of the needle in passing the ligature. 

 The lumbar and sacral arteries chiefly carry on the cir- 

 culation after its ligature. 



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