THE MUSCLES OF THE UROGENITAL REGION IN THE MALE 429 





part of the pelvic fascia. It is perforated, about 2.5 cm. below the symphysis 

 pubis, by the urethra, the aperture for which is circular and about 6 mm. in diameter 

 by the arteries to the bulb and the ducts of the bulbourethral glands close to the 

 urethral orifice; by the deep arteries of the penis, one on either side close to the 

 pubic arch and about halfway along the attached margin of the fascia; by the dorsal 

 arteries and nerves of the penis near the apex of the fascia. Its base is also perfor- 

 ated by the perineal vessels and nerves, while between its apex and the arcuate 

 pubic ligament the deep dorsal vein of the penis passes upward into the pelvis. 



If the inferior fascia of the urogenital diaphragm be detached on either side, 

 the following structures will be seen between it and the superior fascia: the deep 

 dorsal vein of the penis; the membranous portion of the urethra; the Transversus 

 perinsei profundus and Sphincter urethrse membranacese muscles; the bulbo- 

 urethral glands and their ducts; the pudendal vessels and dorsal nerves of the penis; 

 the arteries and nerves of the urethral bulb, and a plexus of veins. 



Fascia of f Su P erior 



-5-g 



diaphragm] 



I schiocavernosus 



Bulbocavernosus 



FIG. 407. Coronal section of anterior part of pelvis, through the pubic arch. Seen from in front. (Diagrammatic.) 



The superior fascia of the urogenital diaphragm is continuous with the obturator 

 fascia and stretches across the pubic arch. If the obturator fascia be traced medially 

 after leaving the Obturator internus muscle, it will be found attached by some of 

 its deeper or anterior fibers to the inner margin of the pubic arch, while its super- 

 ficial or posterior fibers pass over this attachment to become continuous with the 

 superior fascia of the urogenital diaphragm. Behind, this layer of the fascia is 

 continuous with the inferior fascia and with the fascia of Colles; in front it is con- 

 tinuous with the fascial sheath of the prostate, and is fused with the inferior fascia 

 to form the transverse ligament of the pelvis. 



The Transversus perinsei profundus arises from the inferior rami of the ischium 

 and runs to the median line, where it interlaces in a tendinous raphe with its fellow 

 of the opposite side. It lies in the same plane as the Sphincter urethrse membran- 

 acese ; formerly the two muscles were described together as the Constrictor urethras. 



The Sphincter urethras membranaceae surrounds the whole length of the mem- 

 branous portion of the urethra, and is enclosed in the fasciae of the urogenital dia- 

 phragm. Its external fibers arise from the junction of the inferior rami of the pubis 



