The uterus, or womb, is the part of the female reproductive system in which a baby grows. It is above the vagina, between the bladder and rectum. It is about 7 cm long and 5 cm across at the widest point. The uterus is held in place within the pelvis by several ligaments.
The female reproductive system is made up of internal organs, including the vagina, uterus, ovaries and fallopian tubes. It also includes the external genital organs (the parts that make up the vulva). All the internal organs are in the pelvis, which is below the abdomen and between the hip bones.
The uterus is a hollow, muscular organ that is shaped like an inverted pear. It has 3 parts:
- The fundus is the top of the uterus.
- The body is the main part of the uterus and includes the uterine cavity.
- The cervix is the lower, narrow part of the uterus.
The thick wall of the uterus has 3 layers:
The endometrium is the inner layer that lines the uterus. It is made up of glandular cells that make secretions.
The myometrium is the middle and thickest layer of the uterus wall. It is made up mostly of smooth muscle.
The perimetrium is the outer serous layer of the uterus. The serous layer secretes a lubricating fluid that helps to reduce friction. The perimetrium is also part of the peritoneum that covers some of the organs of the pelvis.
The uterus receives a fertilized egg and protects the fetus (baby) while it grows and develops. The uterus contracts to push the baby out of the body during birth.
Every month, except when a woman is pregnant or has reached menopause, the lining of the uterus grows and thickens in preparation for pregnancy. If the woman doesn’t get pregnant, the lining is shed through the cervix into the vagina and out of the body. This is called menstruation. This process continues until menopause.
Expert review and references
American Cancer Society. Endometrial (Uterine) Cancer. 2015: http://www.cancer.org/acs/groups/cid/documents/webcontent/003097-pdf.pdf.
American Society of Clinical Oncology. Uterine Cancer. 2014: http://www.cancer.net/cancer-types/uterine-cancer/view-all.
Martini FH, Timmons MJ, Tallitsch RB. Human Anatomy. 7th ed. San Francisco: Pearson Benjamin Cummings; 2012.