THE ABDOMEN 621 



superior. — ^The membranous part of the urethra, the glands of 

 Cowper, and the compressor urethrae muscle. 



The postero-superior layer is weak, and is formed by the parietal 

 pelvic fascia. It lies about J inch above and behind that layer, 

 and extend.s inwards to the urethra from the inner aspect of each 

 ischio-pubic ramus near the posterior lip, where it is behind the 

 compressor urethrae muscle. Superiorly it is attached to the 

 transverse pelvic or perineal ligament, and its base joins that cf 

 the antero-inferior layer. At each ischio-pubic ramus it is con- 

 tinuous with the parietal pelvic fascia. When it arrives at the 

 urethra it changes its course, and passes backwards over the 

 anterior border of the levator ani muscle to blend with that portion 

 of the visceral pelvic fascia which ensheathes the prostate gland. 

 The postero-superior layer of the triangular ligament is to be 

 regarded as a part of the parietal pelvic fascia. Antero-inferiorly 

 it is in contact with the membranous part of the urethra and 

 compressor urethrae muscle, whilst postero-superiorly it is related 

 to the anterior fibres of the levator ani of each side, and forms the 

 floor of the anterior diverticulum of the ischio-rectal fossa. The 

 structures which pierce this layer are as follows : the membranous 

 part of the urethra in the male, and the vagina and urethra in the 

 female ; and the internal pudic vessels and dorsal nerves of the penis. 



Urethral Opening. — ^Tlus is often a mere cleft, in which cases the 

 postero-superior layer may be described as being arranged in. two 

 symmetrical halves. At this opening or cleft it becomes con- 

 tinuous superiorly with the capsule of the prostate gland. 



openings for the Internal Pudic Vessels and Dorsal Nerves of the 

 Penis. — These are situated close to the base, on either side, near 

 the ischial ramus. 



Structures between the Layers of the Triangular Ligament. — 

 These are as follows : 



1. The membranous portion of the urethra in great part. 



2. The glands of Cowper. 



3. The compressor urethrae muscle. 



4. The internal pudic arteries, each lying close to the ischio- 

 pubic ramus in the compressor urethrae muscle, and each giving 

 off the following branches : (a) the artery of the bulb, which in turn 

 gives off the artery of a Cowper's gland ; (6) the artery of the 

 corpus cavemosiun ; and (c) the dorsal artery of the penis. 



5. A plexus of veins which receives its tributaries from the 

 cms (corpus cavernosum) and bulb, and in which the internal pudic 

 venae comites take their origin. 



6. The deep lymphatics of the penis. 



7. The dorsal nerves of the penis, each of which lies external to the 

 corresponding internal pudic artery. 



Glands of Cowper. — ^These glands are two in number, right and 

 left. They are situated between the two layers of the triangidar 

 ligament, where they lie above the bulb and behind the mem- 

 branous portion of the urethra, one on either side of the median 



