536 



DISSECTION OF THE PELVIS. 



After the vagina has been laid open by an incision along the upper wall, 

 the position of the uterus in that wall, instead of the extremity of the 

 passage, may be remarked ; and the tube may be seen to extend higher 

 on the posterior than the anterior aspect of the cervix uteri. On the inner 

 surface, towards the lower part, is a slight longitudinal ridge both in front 

 and behind, named columns of the vagina. Before the tissue of the vagina 

 has been distended, other transverse ridges or ruga? pass between the 

 columns. The wall of the vagina is thicker anteriorly around the urethra 

 than at any other part of the canal. 



Structure. The vaginal wall is fornied by a spongy erectile tissue, 

 covered externally by a layer of unstriated muscle, and lined by mucous 

 membrane. At its lower end the tube is surrounded by a band of the 

 fibres of the sphincter vaginae muscle (p. 402). 



The erectile tissue is more abundant at the ends than the middle of the 

 vagina, and is greatest in quantity below where it gives increased thick- 

 ness to the wall. Two masses, one on each side of the opening of the 

 vagina, have been described as the semi-bulbs by Taylor (bulbi vestibuli, 

 Kobelt, fig. 186, a). These are elongated bundles of plexiform veins, 

 inclosed in ribrous membrane ; they are about an inch in length from above 

 down, and are situate one on each side of the vestibule, where they are 

 covered on the outer side by the constrictor vagina? (A). At the upper 

 end each is pointed, and communicates with the vessels of the clitoris : 

 and at the lower rounded extremity it joins the venous plexus of the 

 vagina. 



These bodies would answer to the divided bulb of the corpus spongiosum 

 urethra? in the male, each lateral half being thrust aside in the female 

 towards the crus clitoridis by the large aperture of the vagina. 



Fig. 186. 



A. Sphincter vagina muscle. 



B. Clitoris, 

 c. Nymphse. 



a. Semi-bulbs or bulbi vestibuli. 



b. Venous plexus continuous with veins 



of the clitoris (pars intermedia, 

 Kobelt). 



c. Dorsal vein of the clitoris. 



VENOUS PLEXUSES OF THE GKNITAL OKMAXS AND OPEJJING OP THE VAGINA (Kobelt). 



The mucous membrane is continued through the lower aperture to join 

 the integument on the labia majora, and through the os uteri, at the oppo- 

 site end, to the interior of the uterus. Many muciparous glands and fol- 

 licles open on the surface, but these are in greatest abundance at the up- 

 per part. Conical and filiform papilla? exist on the membrane ; and a 

 laminar epithelium gives a covering to it. 



The muscular layer is outside the erectile structure, and consists of lon- 

 gitudinal fibres. Some reach all along the vagina ; others, and these are 



