OF THE PERINEUM. 375 



II. B. Muscles of the Perinaeum in the Female (Fig. 227). 



Transversus perinaei. Erector clitorldis. 



Sphincter vaginae. Compressor urethrae. 



The Transversus perinasi in the female 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 and fore part of the tuberosity of the ischium, and, 

 passing inward, is inserted into the central point of the perinaeum, joining in this 

 situation with the muscle of the opposite side, the External sphincter ani behind, 

 and the Sphincter vaginae in front. 



Nerve-supply. The perineal branch of the internal pudic. 



Actions. By their contraction they serve to fix the central tendinous point of 

 the perinaeum. 



The Sphincter vaginae surrounds the orifice of the vagina, and is analogous 

 to the Accelerator urinae in the male. It is attached posteriorly to the central 

 tendinous point of the perinaeum, where it blends with the External sphincter ani. 

 Its fibres pass forward on each side of the vagina, to be inserted into the corpora 

 cavernosa of the clitoris, a fasciculus crossing over the body of the organ so as to 

 compress the dorsal vein. 



Nerve-supply. The perineal branch of the internal pudic. 



Actions. It diminishes the orifice of the vagina. The anterior fibres contribute 

 to the erection of the clitoris, as they are inserted into and are continuous with the 

 fascia of the clitoris ; compressing the dorsal vein during the contraction of the 

 muscle. 



The Erector clitoridis resembles the Erector penis in the male, but is smaller than 

 it. It covers the unattached part of the crus clitoridis. It is an elongated muscle, 

 broader at the middle than at either extremity, and situated on either side of the 

 lateral boundary of the perinaeum. It arises by tendinous and fleshy fibres from 

 the inner surface of the tuberosity of the ischium, behind the crus clitoridis from 

 the surface of the crus, and from the adjacent portion of the ramus of the ischium. 

 From these points fleshy fibres succeed, which end "in an aponeurosis, which is 

 inserted into the sides and under surface of the crus clitoridis. 



Nerve-supply. The perineal branch of the internal pudic. 



Actions. It compresses the crus clitoridis and retards the return of blood 

 through the veins, and thus serves to maintain the organ erect. 



The triangular ligament (deep perineal fascia) in the female is not so strong as 

 in the male. It is attached to the pubic arch, its apex being connected with the 

 subpubic ligament. It is divided in the middle line by the aperture of the vagina, 

 with the external coat of which it becomes blended, and in front of this is perfor- 

 ated by the urethra. Its posterior border is continuous, as in the male, with the 

 deep layer of the superficial fascia around the Transversus perinrei muscle. 



Like the triangular ligament in the male, it consists of two layers, between 

 which are to be found the following structures : the dorsal vein of the clitoris, 

 a portion of the urethra and the Compressor urethrae muscle, the glands of Bar- 

 tholin and their ducts ; the pudic vessels and the dorsal nerve of the clitoris ; the 

 arteries of the bulbi vestibuli, and a plexus of veins. 



The Compressor urethras (Constrictor urethrce) arises on each side from the 

 margin of the descending ramus of the os pubis. The fibres, passing inward, 

 divide into two sets: those of the fore part of the muscle are directed across the 

 subpubic arch in front of the urethra to blend with the muscular fibres of the 

 opposite side ; while those of the hinder and larger part pass inward to blend with 

 the wall of the vagina behind the urethra. 



Nerve-supply. The perineal branch of the internal pudic. 



