by Dr. Petra Zebroff, Relationship and Sex Therapist
Because women almost never get to see their own vagina, how it looks or works can remain a mystery to many. First of all, the vagina is a potential space, rather than a hole. The anatomy of the vagina is made up of mucosal tissue that seeps lubrication when aroused (analogous to the erection of the penis). To learn more about Male Sexual Anatomy
Researchers used to think that vaginal tissue was not sensitive to touch, but it has now been found to be richly innervated with nerve fibers in three distinct ‘pleasure zones’ — each one resulting in a distinctly different type of pleasure and orgasm. 
1. Lower Vagina (Entrance): The vulva and entrance to the vagina is rich with nerve fibers that work in tandem with the clitoris. Thrusting inside the vagina will automatically stimulate the clitoral structures.
2. Anterior wall of the vagina (where the G-Spot is found): Inside the vagina, on the anterior wall (tummy side) is an area rich with nerve fibers. Pressing firmly on this wall will also stimulate the ‘internal’ clitoris and urethra behind this wall — also known as the G-spot (read more about G-Spot Orgasm in our Orgasms 101 section).
3. Upper Vagina (Cervix and Cul-de-sac): At the furthest point of the vagina is the Vaginal cul-de-sac and Cervix. Stimulating these areas activates completely different nerves than the clitoral area does, causing that deep, whole-body sensation of orgasm.