Cervix

A small, cylindrical organ comprising the lower part and neck of the uterus and separating the body and cavity of the uterus from the vagina. The fibrous and smooth muscle tissue of the cervix creates a form of sphincter, which can stretch during pregnancy and childbirth. The cervical canal runs through the cervix and allows the passage of blood during menstruation and of sperm from the vagina into the uterus; it also forms part of the birth canal during childbirth. After puberty, mucus is secreted from the glandular cells in the canal to assist sperm entry into the upper cervix.