The cervix is the lower part of the womb (uterus). It protrudes into the vagina. The part that protrudes into the vagina is known as the mouth. There is a small opening in the mouth that leads through the cervical canal to the interior cavity of the womb.Its scientific name is the external os of the cervix. The upper opening of the cervix that leads into the womb's cavity is known as the internal os of the cervix. The external os , canal and internal os strectches wide open during child birth but are very narrow ( only a few milimeters in diameter) in the none pregnant woman.
There are numerous mucous glands in the canal. The mucous protects the internal cavity of the womb against bacteria. The thick mucous forms a barrier that protects against ascending bacteria. Only during ovulation is the mucous more watery to allow the passage of sperm cells through the cervix.