252 I'ELVIC LAYER OR FASCIA. 



aponeurosis of the transversalis muscle, to the ligamentum arcuatum 

 internum, and to the bodies of the lumbar vertebrae, leaving arches 

 corresponding with the constricted portions of the vertebrae for the 

 passage of the lumbar vessels. Lower down it passes beneath the 

 external iliac vessels, and is attached along the margin of the true 

 pelvis ; externally, it is connected to the crest of the ilium ; and, infe- 

 riorly, to the outer two-thirds of Poupart's ligament, where it is con- 

 tinuous with the fascia transversalis. Passing beneath Poupart's 

 ligament, it surrounds the psoas and iliacus muscles to their termi- 

 nation, and beneath the inner third of the femoral arch forms the 

 posterior segment of the sheath of the femoral vessels. 



The fascia peloica is attached to the inner surface of the os pubis 

 and along the margin of the brim of the pelvis, where it is continu- 

 ous with the iliac fascia. From this extensive origin it descends 

 into the pelvis, and divides into two layers, the pelvic and obturator. 



Fig. 98.* 



The pelvic layer or fascia, when traced from the. internal surface 

 of the os pubis near to the symphysis, is seen to be reflected inwards 

 to the neck of the bladder, so as to form the anterior vesical liga- 

 ments. Traced backwards, it passes between the sacral plexus of 

 nerves and the internal iliac vessels, and is attached to the anterior 

 surface of the sacrum ; and followed from the sides of the pelvis, it 

 descends to the base of the bladder and divides into three layers, 

 one ascending, is reflected to the side of that viscus, encloses the 



* A transverse section of the pelvis, showing the distribution of the pelvic fascia. 1. 

 The bladder. 2. The vesiculse seminales divided across. 3. The rectum. 4. The 

 iliac fascia covering in the iliacus and psoas muscles (5) ; and forming a sheath for the 

 external iliac vessels (6). 7. The anterior crural nerve excluded from the sheath. 8. 

 The pelvic fascia. 9. Its ascending layer, forming the lateral ligament of the bladder 

 of one side, and a sheath to the vesical plexus of veins. 10. The recto-vesical fascia 

 of Mr. Tyrrell formed by the middle layer. 11. The inferior layer surrounding the 

 rectum and meeting at the middle line with the fascia of the opposite side. 12. The 

 levator ani muscle. 13. The obturator internus muscle, covered in by the obturator 

 fascia, which also forms a sheath for the internal pudic vessels and nerve (14). 15. 

 The layer of fascia which invests the under surface of the levator ani muscle, the anal 

 fascia. 



