Cross-sectioned uterus anchored to the abdominal wall by its ligaments. The uterus is a thick-walled organ which serves to receive, retain and nourish a fertilized ovum. The main structure of the uterus is called the body, the superior rounded aspect, the fundus, and the narrowed region between the body and cervix is the isthmus. Semen can enter through the vagina inferiorly through the cervical canal to the cavity of the uterus. The uterus is anchored by ligaments which support it within the pelvis.