THE PERINEUM, FEMALE. 431 



behind, forming the pouch of Doug-las ; below, the vagina 

 is separated from the rectum for its last inch by the fibrous 

 structures which, taken together, form the " perineal body ; " 

 in the middle portion the vagina lies in contact with the 

 rectum. At the sides : Above, the vagina is crossed by the 

 ureters from above downward and forward ; below, it is 

 embraced by the levatores ani muscles. 



The mucous membrane (probably modified integument) is 

 thrown into longitudinal ridges upon the anterior and poste- 

 rior walls of the vagina. These ridges are called the columns 

 rugarum. They extend upward from the vaginal orifice. 



The veins form a plexus about the vagina and commu- 

 nicate with the hemorrhoidal and vesical plexuses. 



The arteries are from the anterior division of the internal 

 iliac, viz. : vaginal, internal pudic, vesical, and uterine. 



The nerves are from the internal pudic, the fourth sacral, 

 and the hypogastric sympathetic plexus. 



The Perineal Body. Fig. 85. 



This is the mass of elastic, fibrous, and connective tissue, 

 with the adjacent portions of muscles, which fills in the 

 space between the lower end of the vagina and vaginal 

 orifice in front and the rectum and anus behind. It is tri- 

 angular in anteroposterior section, the base at the integu- 

 ment, the apex at the junction of the vaginal and rectal 

 walls. The sides of the triangle measure about an inch. 



The Uterus. See Pelvic Viscera. 



The Female Urethra. Figs. 85, 86. 



Is about one and one-half inches long and one-fourth 

 inch in diameter. It lies along the anterior wall of the 

 vagina. It opens into the bladder three-fourths of an inch 

 behind the middle of the pubic symphysis, and externally 

 in the middle line just in front of the orifice of the vagina. 



