What is the name of the narrow, lower section of the uterus that opens into the vagina?

The cervix is the narrow, lower section of the uterus that serves as the passageway between the uterus and the vagina. This structure plays a crucial role in various physiological processes, including menstruation, childbirth, and the reproductive cycle. During menstruation, the cervix opens slightly to allow menstrual fluid to exit the uterus, and during childbirth, it dilates to facilitate the passage of the baby from the uterus through the vagina. Additionally, the cervix produces mucus that can change in consistency during the menstrual cycle, influencing sperm movement and providing protective barriers against pathogens. This anatomical feature is vital for reproductive health and is often a focus in gynecological examinations.

In contrast, the fundus is the uppermost rounded portion of the uterus, the body refers to the main cavity of the uterus that contains the developing fetus during pregnancy, and the endometrium is the inner lining of the uterus where implantation of the embryo occurs. Each of these structures serves specific functions within the reproductive system, but none serve as the passage to the vagina.