THE PEL VIC FASCIA 



453 



Relations. By its deep, upper, or pelvic surface the Levator ani is in relation with the 

 pelvic fascia, which separates it from the blade 1 ;r, prostate, rectum, and peritoneum. By its 

 superficial, lower, or perineal surface, it forms the inner boundary of the ischiorectal fossa, and 

 is covered by a thin layer of fascia, the ischiorectal or anal fascia, given off from the obturator 

 fascia. Its posterior border is free and separated from the Coccygeus muscle by a cellular inter- 

 space. Its anterior border is separated from the muscle of the opposite side by a triangular 

 space, through which the urethra, and in the female the vagina, pass from the pelvis. 



The Levator ani may be divided into iliococcygeal and pubococcygeal parts. 



The Iliococcygeus arises from the ischial spine and from the posterior part of the pelvic fascia, 

 and is attached to the coccyx and anococcygeal raphe; it is usually thin, and may fail entirely, 

 or be largely replaced by fibrous tissue. An accessory slip at its posterior part is sometimes 

 named the 'lliosacralis. The Pubococcyyeus arises from the back of the pubis and from the 

 anterior part of the pelvic fascia, and " is directed backward almost horizontally along the side 

 of the anal canal toward the coccyx and sacrum, to which it finds attachment. Between the 



ANTERIOR SACRO- 

 COCCYGEAL LIGAMENT 



GREAT SACRO- 

 SCIATIC LIGAMENT 



t|,OCOCCYGEUS(M. ILIOCOCCYGEUS);* QBTUR. 

 \N N?' FASCIA 



OBTURATOR 

 CANAL 



PERIOR LAYER 

 F TRIANGULAR 

 LIGAMENT 



FIG. 345. The levator ani of the male, viewed from above. (Spalteholz.) 



termination of the vertebral column and the anus the two pubococcygeal muscles come together 

 and form a thick, fibromuscular layer lying on the raphe formed by the iliococcygei " (Thompson). 

 The greater part of this muscle is inserted into the coccyx and into the last one or two pieces of 

 the sacrum. This insertion into the vertebral column is, however, not admitted by all observers. 

 The fibres which form a sling for the rectum are named the Puborectalis or Sphincter recti. 

 They arise from the lower part of the symphysis pubis, and from the upper layer of the triangular 

 ligament. They meet with the corresponding fibres of the opposite side around the lower part 

 of the rectum, and form for it a strong sling. 



Nerve-supply. The Levator ani is supplied by a branch from the fourth sacral nerve and 

 by a branch which is sometimes derived from the perineal, sometimes from the inferior hemor- 

 rhoidal division of the pudic nerve. 



The Coccygeus (m. coccygeus} (Fig. 345) is situated behind and parallel with 

 the preceding. It is a triangular plane of muscular and tendinous fibres, arising 



