The vagina is the passage (birth canal) connecting the uterus (womb) to the outside of the body. Usually about 8 cm long, it is joined to the uterus at the cervix, and passes through the lower part of the woman’s body behind the urethra and bladder and in front of the rectum. It is the passage into which the male penis is inserted during sexual intercourse. Vaginal secretions are released during sexual arousal and it can expand to facilitate intercourse. Sperm ejaculated during intercourse travel through the cervix and into the uterus and Fallopian tubes to fertilise an egg if one has been released.
The lining of the vaginal wall is made up of a moist mucous membrane arranged in folds, which enable its muscular tissue to expand for the purposes of sexual intercourse and childbirth. The muscles in the wall of the vagina will also contract in spasms when a woman has an orgasm during intercourse. This rhythmic contraction aids the movement of the ejaculated sperm towards the cervix and uterus.
In children the external opening to the vagina is partly covered by a thin mucous membrane called the hymen. This will be broken at the time of first sexual intercourse, or it may break spontaneously earlier than this.