Lecture Notes

The vagina is a flexible muscular structure that extends three to five inches back and upward from the vaginal opening. It serves as the birth canal through which the infant is born. It also allows menstrual flow to pass from the uterus, and encompasses the penis or other object during sexual expression. When unaroused the walls of the vagina are relaxed and collapse together. However, during sexual arousal the inner two-thirds of the vagina expand, and the pressure from engorgement causes many small blood vessels within the vaginal wall to produce lubrication. Lubrication can occur within 10 to 30 seconds of sexual stimulation. The lower third of the vagina is known as the introitus. This is where the majority of sensory nerve endings are concentrated, and is most sensitive to erotic pleasure and touch. In contrast, the inner two-thirds of the vagina have virtually no nerve endings. This is why a woman cannot feel a tampon when inserted deep into the vagina. Prior to first intercourse or other form of penetration, the introitus is partially covered by a thin membrane containing a relatively large number of blood vessels. This membrane is known as the hymen. The hymen typically has one or several perforations, which allows menstrual blood and mucus secretions to flow out of the vagina. The hymen may be stretched or ruptured by tampon insertion, by the woman's self-manipulation, by a partner during non-coital sexual activity, by accident, or by a healthcare provider conducting a routine pelvic exam. For many cultures, it was or is important for a woman's hymen to be intact on her wedding day as a symbol of purity. The Grafenberg spot, or G-spot, is an area within the vagina reported by many women to be erotically sensitive. The site is located on the front wall of the vagina, midway between the pubic bone and the cervix on the vaginal side of the urethra. The area varies in size from a small bean to half a walnut. It is thought that the close contact between the internal root of the clitoris and the anterior vaginal wall is what leads to the intense and extreme pleasure in women who report sexual enjoyment from contact with the site. However, an exact gland or site has not been found in all women, nor do all women experience pleasure when the site is massaged.