374 ABDOMEN 



genital diaphragm about half an inch below the symphysis pubis, and a 

 little way lateral to the middle line. 



Urogenital Diaphragm (O.T. Triangular Ligament). A 

 good view is now obtained of the lower fascia of the urogenital 

 diaphragm. Owing to the greater width of the pubic arch, it 

 is a more extensive membrane than in the male (see Fig. 140). 

 It does not possess the same strength, however, and is not so 

 perfect, seeing that it is pierced by the vaginal canal. 



In the middle line it is pierced, fully an inch below the 

 symphysis pubis, by the urethra, and immediately below the 

 urethral opening by the wide vagina. Its base is perforated 

 by the superficial perineal vessels and nerves, whilst on each 

 side the internal pudendal artery and the dorsal nerve of the 

 clitoris pierce it about half an inch below the symphysis. 



The dorsal vein of the clitoris passes backwards through 

 an oval opening between its upper border, the so-called trans- 

 verse ligament of the pelvis, and the arcuate ligament of the 

 pubis. 



As in the male, the urogenital diaphragm consists of the 

 deep transverse muscles of the perineum and the sphincter 

 urethrae membranaceae, enclosed between a superficial and a 

 deep layer of fascia. Between the two fasciae lie portions of 

 the urethra, and the vagina and parts of the internal pudendal 

 vessels and the dorsal nerves of the clitoris. The two fascial 

 layers are fused, as in the male, a short distance below the 

 arcuate ligament of the pubes, where their united margins 

 form the transverse ligament of the pelvis and again, 

 posteriorly, at the base of the diaphragm. 



Dissection. The inferior fascia of the urogenital diaphragm should be 

 reflected upon one side. Detach it from the margin of the pubic arch and 

 throw it medially. The structures between the two layers may now be 

 examined. 



Urethra Muliebris. The female urethra is a short canal, 

 which extends from the neck of the bladder to its orifice at the 

 base of the vestibule. It measures about one and a half 

 inches in length, and has an oblique and slightly curved 

 course from above downwards and forwards. The con- 

 cavity of the curve is directed forwards. So close is its 

 relation to the anterior wall of the vagina, that it may almost 

 be said to be embedded in it. 



At the present stage of the dissection, the urethral canal is 

 covered by the fibres of the sphincter urethrae muscle. 



