594 



ABDOMEN 



its apex downwards. In size it is variable, but its average 

 dimensions are : length, about one and a quarter inches 

 (31 mm.) from base to apex; breadth, one and a half inches 

 (37 mm.) from side to side at its broadest part. 



Position. The prostate rests upon the anterior aspect of 

 the lowest part of the rectum. It is about an inch and a 

 half distant from the anus, whilst its anterior border lies 



Symphysis pubis 



Tubercle of pubis 



Central point of 

 perineum' 



Sphincter ani externus 



FIG. 239. Dissection of the two Levatores Ani. The pelvis is tilted forwards 

 and the pubic arch has been removed. Both layers of the triangular 

 ligament, 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. 



three-quarters of an inch behind the lower part of the 

 symphysis pubis. As already mentioned, the prostate is en- 

 closed in a strong fibrous sheath derived from the pelvic 

 fascia. This sheath is firmly fixed not only by the pubo- 

 prostatic ligaments, which form a part 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 uro-genital 

 diaphragm. These connections of the sheath prevent the 

 prostate altering its position in response to the continual 



