The cervix is part of the female reproductive system. Around in length, it is the lower narrower part of the uterus continuous above with the broader upper part—or body—of the uterus. The lower end of the cervix bulges through the anterior wall of the vagina, and is referred to as the vaginal portion of cervix (or ectocervix) while the rest of the cervix above the vagina is called the supravaginal portion of cervix. A central canal, known as the cervical canal, runs along its length and connects the cavity of the body of the uterus with the lumen of the vagina. The openings are known as the internal os and external orifice of the uterus (or external os) respectively. The mucosa lining the cervical canal is known as the endocervix, and the mucosa covering the ectocervix is known as the exocervix. The cervix has an inner mucosal layer, a thick layer of smooth muscle, and posteriorly the supravaginal portion has a serosal covering consisting of connective tissue and overlying peritoneum.