The Internal Clitoris

and a bit more here http://blog.museumofsex.com/the-internal-clitoris/ and here http://io9.com/5876335/until-2009-the-human-clitoris-was-an-absolute-mystery

...Many women can bring themselves to orgasm without ever inserting anything inside of themselves. They are causing their internal clitoris to become erect and likely stimulating their glans, bulbs, and crura by rubbing themselves on the outside. The corpus cavernousum is the additional erectile tissue encompassing the vagina, and greatly erogenous when stimulated internally.

Let’s also remember, female orgasm is not solely about the clitoris and vagina either. It is far more complex and also involves the workings of multiple nerves, tissues, muscles, reflexes, and mental effort. Some women can think themselves to orgasm. Others can orgasm simply by flexing their pelvic muscles. Considering all the components involved plus the variability of human beings and their anatomies, it’s extremely important to remember no two people are the same. What works for one woman may not work for another. In other words, it’s all custom under the hood...