External genitalia

Internal gynecologic organs

The uterus is a hollow, pear-shaped, muscular structure that lies in the true pelvis between the bladder and the rectum. Its function is to allow for childbearing.

The main body of the uterus is the corpus. The cephalic portion of the corpus is called the fundus. The fallopian tubes enter the fundus laterally at the cornua. Caudally, the corpus narrows to an isthmus, which is continuous with the uterine cervix. The cervix is the lower, narrow portion of the uterus. The cervix is predominantly fibrous tissue. The cervical canal opens into the vagina at the external os of the cervix. In nulliparous women the os is small and round.

The endometrium consists of tubular glands, blood vessels, and fine connective tissue (Mishell, Ryan).

In nulliparous women, the external cervical os is small and round. After vaginal delivery, the os becomes wider and gaping. The endometrium is the soft lining of the corpus.

The positions of the uterus and cervix are shown below relative to the other pelvic structures.