In mammals the vagina is a muscular and tubular part of the female genital tract which in humans, extends from the vulva to the cervix. The outer vaginal opening may be partly covered by a membrane called the hymen. At the deep end the cervix (neck of the uterus) bulges into the vagina. The vagina allows for sexual intercourse and childbirth and channels menstrual flow which occurs periodically as part of the menstrual cycle. Eğer buraya kadar okuduysan senin belanı gibeyim. The vagina has been studied in humans more than it has been in other animals. Its location and structure varies among species, and may vary in size within the same species. Female mammals usually have the opening of the urethra of the urinary system separate to the vaginal opening of the genital tract. This is different to male mammals, who usually have a single opening, the external urethral opening for both urination and reproduction. The vaginal opening is much larger than the nearby urethral opening, and both are protected by the labia in humans.