virgins menstruate?

theres so much i don't know about girls i thought they had that hymen thing blocking the way

If the hymen is completely sealed, which is a rarity, a virgin CAN have trouble passing menses. Corrective minor surgery fixes the problem. In most girls/women though, the hymen only partially covers the opening of the vagina. There are many forms of the hymen, including perforate (tiny openings all in the hymen), septate (a hymen with two openings), and incomplete (a hymen that slightly covers the vaginal opening). Every hymen is different, and most allow for the passing of menses. Sometimes by the time a girl menstruates for the first time, her hymen may have already been torn. A missing or torn hymen is NOT an indicator of sexual activity, in some cases, a girl may be born without one. The hymen can be torn by activities such as bicycling, horseback riding, doing the splits, and a host of other normal activities.