MUSCLES OF THE PERINEUM. 



T79 



along the canal of the urethra. The middle fibres are supposed, by Krause, to 

 assist in the erection of the corpus spongiosum, by compressing the erectile tissue 

 of the bulb. The anterior fibres, according to Tyrrel, also contribute to the 

 erection of the penis, as they are inserted into, and continuous with, the fascia 

 penis, compressing the dorsal vein during the contraction of the muscle. 



Fig. 391. The Superficial Muscles and Vessels of the Perineum. 



Sacra -Sciaii 



Superficial Perintal A rttr j 

 Superficia.1 Perineal A'erve 

 Internal Pudie Nerve 

 Internal PuJic Arte, ry 



The Erector Penis covers the unattached part of the crus penis. It is an 

 elongated muscle, broader in the middle than at either extremity, and situated on 

 either side of the lateral boundary of the perineum. It arises by tendinous and 

 fleshy fibres from the inner surface of the tuberosity of the ischium, behind the 

 crus penis, from the surface of the crus, and from the adjacent portion of the 

 ramus of the pubes. From these points, fleshy fibres succeed, which end in an 

 aponeurosis which is inserted into the sides and under surface of the crus penis. 

 This muscle compresses the crus penis, and thus serves to maintain this organ 

 erect. 



The Transversus Perinei is a narrow muscular slip, which passes more or less 

 transversely across the back part of the perineal space. It arises by a small 

 tendon from the inner side of the ascending ramus of the ischium, and, passing 

 obliquely forwards and inwards, is inserted into the central tendinous point of the 

 perineum, joining in this situation with the muscle of the opposite side, the 

 Sphincter ani behind, and the Accelerator urinae in front. 



Between the muscles just examined, a triangular space exists, bounded internally 

 by the Accelerator urinae, externally by the Erector penis, the base corresponding 

 to the Transversus perinei. The floor of this space is formed by the triangular 

 ligament of the urethra (deep perineal fascia), and, running from behind forwards 

 in it, are the superficial perineal vessels and nerves, the transversus perinei artery 

 coursing along the posterior boundary of the space, resting upon the Transversus 

 perinei muscle. 



