The cervix is the lower part of the uterus, protruding into the vagina. So it’s located inside the vagina, all the way up.
The cervix is the entrance to the womb.
If you insert your finger far back into the vagina you can feel it. It’s like touching the tip of your nose.
The cervix looks like the tip of the penis: rounded and firm with a small opening (the os) in the centre. This very small opening, about the size of a pinhead, allows menstrual blood to flow out of the womb and sperm to enter.
The cervix closes the vagina off at the top. So a condom that has slipped off or a tampon can never be lost, as some girls fear. Only during childbirth does the cervix really open up.