THE MUSCLES AND FASCIAE OF THE PELVIS 



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with its fellow of the opposite side to form the greater part of the floor of the pelvic 

 cavity. It supports the viscera in this cavity, and surrounds the various structures 

 which pass through it. It arises, in front, from the posterior surface of the superior 

 ramus of the pubis lateral to the symphysis; behind, from the inner surface of the 

 spine of the ischium; and between these two points, from the obturator fascia. 

 Posteriorly, this fascial origin corresponds, more or less closely, with the tendinous 

 arch of the pelvic fascia, but in front, the muscle arises from the fascia at a vary- 

 ing distance above the arch, in some cases reaching nearly as high as the canal 



Superior glutceal vessels 



Obturator nerve 

 and vessels 



Left lobe of prostate (cut) 



Anococcygeal raphe 



Fia. 404. Left Levator ani from within. 



for the obturator vessels and nerve. The fibers pass downward and backward 

 to the middle line of the floor of the pelvis; the most posterior are inserted into the 

 side of the last two segments of the coccyx; those placed more anteriorly unite 

 with the muscle of the opposite side, in a median fibrous raphe (anococcygeal 

 raphe), which extends between the coccyx and the margin of the anus. The middle 

 fibers are inserted into the side of the rectum, blending with the fibers of the 

 Sphincter muscles; lastly, the anterior fibers descend upon the side of the prostate 

 to unite beneath it with the muscle of the opposite side, joining with the fibers of 

 the Sphincter ani externus and Transversus perinsei, at the central tendinous point 

 of the perineum. 



