The cervix is part of a woman's reproductive system. It's in the pelvis. The cervix is the lower, narrow part of the uterus (womb).
The cervix is a passageway:

* The cervix connects the uterus to the vagina. During a menstrual period, blood flows from the uterus through the cervix into the vagina. The vagina leads to the outside of the body.
* The cervix makes mucus. During sex, mucus helps sperm move from the vagina through the cervix into the uterus.
* During pregnancy, the cervix is tightly closed to help keep the baby inside the uterus. During childbirth, the cervix opens to allow the baby to pass through the vagina.
http://healthavenue..com/2010/11/causes-symptoms-of-cervical-cancer.html