452 PRACTICAL ANATOMY. 



The deep layer of the deep perineal fascia is a delicate 

 membranous structure, which is derived from the deep layer 

 of the superficial fascia as it curves around the posterior 

 border of the transversus perinei muscles. It passes to 

 the anterior and upper surface of the prostate gland. 

 The perineal fasciae are very simple in their arrange- 

 ment. They inclose the important structures of the 

 perineum. When the deep layer of the superficial fascia 

 is removed the following structures are brought into 

 view : The transversus perinei, erector penis, and accel- 

 erator urinae muscles ; the transverse and superficial 

 perineal arteries and nerves, the corpus spongiosum 

 and bulb, and the corpora cavernosa. The transversus 

 perinei arise from the inner surfaces of the tuberosities of 

 the ischia and pass transversely inward, and are inserted 

 on the central tendon of the perineum. They are each 

 about as thick as a lead-pencil. The erector penis on each 

 side arises from the inner surface of the tuberosity of the 

 ischium and is broadly inserted upon the corpus caver- 

 nosum. 



The accelerator urinae is a bipenniform muscle ; it 

 surrounds the corpus spongiosum and bulb, and may be 

 said to arise from the central tendon ; it is inserted at 

 the sides of the crus penis. In the triangular interval 

 between the accelerator urinae and erector penis the 

 superficial perineal artery and nerve are seen. The floor 

 of this triangle is the superficial layer of the deep perineal 

 fascia (the triangular ligament). When the accelerator 

 urinae is removed, the corpus spongiosum and bulb of 

 the urethra are brought into view ; they are in the median 

 line, and inclose the urethra. When the superficial layer 

 of the deep perineal fascia (triangular ligament) is re- 

 moved, the following structures are brought into view : 

 Artery of the bulb, Cowper's gland, internal pudic artery, 



