The cervix (Latin: ostium uteri) in the female body is respectively the opening of the cervix into the uterus and into the vagina. In the course of pregnancy and during child birth, the cervix and its opening are of particular importance.
What is the cervix?
The so-called internal cervix is the upper opening of the cervix into the cavity of the uterus, and the external cervix is the lower opening of the cervix towards the vagina. This is surrounded by a thick layer of mucous membrane that protrudes into the roof of the vagina, preventing germs from entering the uterus. Before a woman has given birth, the external cervix is dimpled round in shape, then after the first birth it is split transversely like a mouth. During a woman’s cycle, the external cervix protrudes up to three centimeters into the vagina on infertile days and can be felt from the outside.
Anatomy and structure
As part of the cervix, the cervix has a wall composed of three layers. The outer wall is a mucosal layer with glands that changes in structure during the menstrual cycle. Under the mucous membrane is a muscular layer in which the muscles are arranged in spirals. The lowest of the three layers is formed by a membrane bounding the abdominal cavity. The area in the cervix between the inner and outer cervix is also called the cervical canal.
Function and tasks
The external cervix plays a role during sexual intercourse because during a woman’s orgasm, it dips into the expelled semen in undulating motions to help transmit sperm. In pregnancy, the cervical canal is tightly closed with the inner and outer cervix. In this way, the penetration of germs into the amniotic cavity is prevented. In a pregnant woman, the length of the cervix should be more than 2.5 cm, because if it is more shortened, premature birth may occur due to the premature opening of the cervix without labor. When birth begins with the so-called opening phase, contractions ensure that the cervix is initially dilated. After a shortening of the cervical canal, the inner cervix is the first to stretch. Eventually, the outer cervix begins to open as well. The last phase of birth, called the expulsion phase, begins with finally a complete opening of the external cervix.
Diseases, ailments and disorders
Various complaints and diseases can occur in connection with the cervix, even outside pregnancy and childbirth. At the external cervix, where the smooth skin of the vagina borders the mucosa of the cervical canal, there is a zone of tissue where pathogens can cause changes in the skin structure (called “dysplasias”). These skin changes can be mild (stage I), moderate (stage II) or severe (stage III). Severe dsyplasias can transform into precancerous lesions (stage IV) and into cancer (stage V). Diseases of the cervix are usually detected during gynecological screening, during which smears are taken. These can detect the skin changes at a very early stage, so treatment can be started before precancerous lesions develop. It usually consists in removal of the affected tissue. The germs that trigger dysplasia are usually so-called “human papilloma viruses” (HPV), of which there are over 30 different types. They are transmitted primarily through sexual intercourse, and no effective drug treatment exists as yet. However, young girls can be vaccinated against certain HPV types before having sexual intercourse for the first time. HPV viruses are also responsible for the formation of genital warts (so-called condylomas or genital warts), which in turn can also cause skin changes at the cervix. Normally, these warts can be successfully treated with solutions or creams, so that dysplasia of the tissue of the cervix is prevented.
