PELVIS MINOR 



449 



of it, but also, at the apex of the gland, by the continuity 

 which is established between the sheath and the upper fascia 

 of the urogenital diaphragm. The connections of the sheath 

 prevent the prostate altering its position in response to the 

 continual changes which occur in the state of the distension 

 of the bladder. It is a matter of importance to notice that 

 the prostate lies loosely in its sheath. Only in the median 



Symphysis pubis 



Tubercle of pubis 



Obturator 

 membrane 



Central point of 

 perineum' 



Sphincter ani externus 



FIG. 214. Dissection of the two Levatores Ani. The lower part of the pelvis 

 is tilted forwards and the pubic arch has been removed. Both fasciae of 

 the urogenital diaphragm, the parts in relation to them, and the pubic 

 origins of the levatores ani, have also been taken away. The portion of 

 bone removed is indicated by the dotted lines. 



' 



plane, in front, and around the urethra as it emerges from the 

 gland, is there any degree of adhesion between the prostate 

 and its fascial envelope. 



Within the sheath, and attached more closely to its inner 

 surface than to the prostate, is a plexus of thin -walled 

 veins, called the pudendal plexus (Fig. 199). The plexus is 

 spread over the anterior border and the lateral surfaces of 

 the prostate, and is denser in the latter situations than in the 

 former. It receives the dorsal vein of the penis ; it com- 



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