THE VULVA 603 



THE VULVA 



The vulva or urogenital sinus (Vestibulum vaginae) is the terminal part of the 

 genital tract. -^ It is continuous in front with the vagina, and opens externally at 

 the vulvar cleft below the anus. There is no external line of demarcation between 

 the vagina and vulva. The tube is four or five inches (ca. 10-12 cm.) in length, 

 measured from the external urethral orifice to the ventral commissure; dorsally 

 (from a pojnt vertically opposite to the external urethral orifice) it is considerably 

 shorter. ilTt is related dorsally to the rectum and anus, ventrally to the pelvic floor, 

 and laterally to the sacro-sciatic ligament, the semimembranosus muscle, and the 

 internal pudic artery. The external orifice, the vulvar cleft (Rima vulvae), has the 

 form of a vertical slit, four or five inches (ca. 10-12 cm.) high, and is margined 

 by two prominent rounded lips, the labia vulvae. The labia meet above at an acute 

 angle, forming the dorsal commissure (Commissura dorsalis), which is about two 

 inches (ca. 5 cm.) below the anus. They unite below to form the thick, rounded 

 ventral commissure (Commissura ventralis) , which lies about two inches (ca. 5 cm.) 

 behind and below the ischial arch. When the labia are drawn apart, a rounded 

 body, about an inch (ca. 2.5 cm.) wide, is seen occupying a cavity in the ventral 

 commissure ; this is the glans clitoridis, the homologue of the glans penis, and the 

 cavity in which it lies is the fossa clitoridis. The roof of the fossa is formed by a 

 thin fold, which overlies the glans clitoridis and is attached centrally to it. At 

 the anterior extremity of the ventral wall of the vulva, i. e., four or five inches (ca. 

 10-12 cm.) from the ventral commissure, is the external urethral orifice (Ori- 

 ficium urethrse externum).^ It readily admits the finger and is very dilatable. It 

 is covered by a fold of mucous membrane, the free edge of which is directed back- 

 ward (Fig. 533). 



Structure. — The labia are covered by thin, pigmented, smooth skin, which is 

 richly supplied with sebaceous and sweat glands. This is continuous at a distance 

 of about half an inch (ca. 1-1.5 ^m.) from the free edge with a thin, glandless 

 mucous membrane. Under the -^kin there is a layer of striped muscle, the con- 

 strictor vulvae; this fuses above with the sphincter ani, and embraces the clitoris 

 below, spreading out laterally at the ventral commissure. It constricts the vulvar 

 orifice and elevates the clitoris. The constrictor vestibuli muscle embraces the 

 /vulva in front of the preceding; it is deficient dorsally and is joined on either side 

 by a band of unstriped muscle, the suspensory ligament of the anus. It constricts 

 the vulva. Within this there is an unstriped muscular coat, most of the bundles 

 of which are circular. Chiefly between this coat and the mucous membrane there 

 is in the lateral wall, just in front of the labia, a flattened, oval body, the bulbus 

 vestibuU (Fig. 578); this is an erectile structure, homologous with the corpus 

 cavernosum urethrae of the male. It is about two and a half to three inches (ca. 

 6-8 cm.) long, and an inch or more (ca. 3 cm.) wide. It is similar in structure to 

 the bulb of the corpus cavernosum urethrae of the male, and is supplied with blood 

 by a large branch of the internal pudic artery. The mucous membrane of the 

 vulva is reddish in color, and forms longitudinal and transverse folds. It presents 

 ventrally two linear series of small papillae which converge toward the ventral 

 commissure; these mark the orifices of the ducts of the glandulae vestibulares 

 minores. On either side of the dorsal wall is a group of eight to ten larger promi- 

 nences on which the ducts of the glandulae vestibulares majores open (Fig. 533). 



Quite exceptionally there may be found on either side of the urethral orifice the openings of 

 the canals of Gartner (Ductus epoophori longitudinales) . 



1 The term vulva is used here in the sense in which it is understood generally by EngUsh 

 and French veterinarians. In the German works it is applied only to the labia and other struc- 

 tures around the external orifice of the urogenital sinus, while the sinus itself is termed the vestibule 

 of the vagina (Vestibulum vaginse). 



2 Also termed the meatus urinarius. 



