Vaginal fornix

The fornices of the vagina are the superior portions of the vagina, extending into the recesses created by the vaginal [portion of cervix]. There is an anterior fornix and a posterior fornix. The word is Latin for 'arch'.

Sexuality

During sexual intercourse in the missionary position, the tip of the penis may reach the anterior fornix, while in the rear-entry position it may reach the posterior fornix.
The anterior fornix is also called the a-spot, an analogue to the g-spot, which is closer to the vaginal opening, and also on the anterior side of the vagina.