To accommodate smoother penetration of the vagina during sexual intercourse or other sexual activity, vaginal moisture increases during sexual arousal in human females and also in other female mammals.This increase in moisture is vaginal lubrication, which reduces friction.The vaginal opening is much larger than the nearby urethral opening, and both are protected by the labia in humans.
Where the vaginal lumen surrounds the cervix of the uterus, it is divided into four continuous regions or vaginal fornices; these are the anterior, posterior, right lateral, and left lateral fornices.
The effects of vaginal intercourse and childbirth on the hymen are variable.
If the hymen is sufficiently elastic, it may return to nearly its original condition.
The vaginal canal then travels upwards and backwards, between the urethra at the front, and the rectum at the back.
Near the upper vagina, the cervix protrudes into the vagina on its front surface at approximately a 90 degree angle.