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pl. vaginaevaginas [L. vagina, sheath]
A musculomembranous tube that forms the passageway between the cervix uteri and the vulva.
VAGINA AND OTHER FEMALE ORGANS
In the uppermost part, the cervix divides the vagina into four small vaulted cavities, called fornices: two lateral, the anterior, and the posterior. The bladder and urethra are adjacent to the anterior wall of the vagina, and the rectum is behind the posterior wall. The cavity of the vagina is a potential space; the walls are usually in contact with each other. Close to the cervix uteri the walls form a horizontal crescent shape, at the midpoint an H shape, and close to the vulva the shape of a vertical slit. The vaginal mucosa is stratified squamous epithelium that is very resistant to bacterial colonization. This lining is in folds called rugae, and the connective tissue external to it also permits stretching. The blood supply of the vagina is furnished from the inferior vesical, inferior hemorrhoidal, and uterine arteries. Except for the area close to the entrance, the vaginal tissue and mucosa contain few, if any, sensory nerve endings. The vagina is a passage for the insertion of the penis, for the reception of semen, and for the discharge of the menstrual flow. It also serves as the birth canal.