Vagina
The vagina is an elastic, muscular tube. It starts at the cervix and ends at the vulva. It is about  wide, and  long. During sexual intercourse and childbirth, the vagina gets wider and bigger. It has to be lubricated to stay clean and allow sexual intercourse and childbirth. It is lubricated partially by the Bartholin's glands. This lubrication also allows sperm easier access to fertilize an ovum.