In amphibians, birds, reptiles and monotremes, the cloaca is the single external opening for the gastrointestinal tract, the urinary, and reproductive tracts.To accommodate smoother penetration of the vagina during sexual intercourse or other sexual activity, vaginal moisture increases during sexual arousal in human females and other female mammals.
Because of this, the collapsed vagina has an H-shaped cross section.
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 intercourse and childbirth on the hymen are variable.
Where it is broken, it may completely disappear or remnants known as carunculae myrtiformes may persist.
For these reasons, virginity cannot be definitively determined by examining the hymen.
The length of the vagina varies between women of child-bearing age.
By its dictionary and anatomical definitions, however, vagina refers exclusively to the specific internal structure, and understanding the distinction can improve knowledge of the female genitalia and aid in healthcare communication.
Although by its dictionary and anatomical definitions, the term vagina refers exclusively to the specific internal structure, it is colloquially used to refer to the vulva or to both the vagina and vulva.
The vaginal opening is at the posterior end of the vulval vestibule, behind the urethral opening.
The opening to the vagina is normally obscured by the labia minora (vaginal lips), but may be exposed after vaginal delivery.
The vagina and vulva have evoked strong reactions in societies throughout history, including negative perceptions and language, cultural taboos, and their use as symbols for female sexuality, spirituality, or regeneration of life.