31.20 : Uterus and Cervix

The uterus, commonly called the womb, is a vital reproductive organ in females designed to provide a nurturing environment for the implantation and growth of an embryo. It is shaped like a hollow pear and positioned between the urinary bladder and the rectum. The uterus's structure allows it to support and protect a developing fetus throughout pregnancy.

The uterus is securely anchored within the pelvic cavity by paired broad ligaments on either side. It is further stabilized by three pairs of suspensory ligaments: the cardinal, uterosacral, and round ligaments. These connections hold the uterus in place and provide structural integrity and support as it enlarges during pregnancy.

A non-gravid uterus typically measures about 7-8 cm in length, 5 cm in width, and 2.5 cm in thickness, although these dimensions vary based on factors such as age and pregnancy history. The upper portion of the uterus is called the fundus, which sits above the points where the uterine tubes attach. Below the fundus is the body of the uterus, which houses the uterine cavity. This cavity narrows at the isthmus before extending into the cervix, the tubular part of the uterus that opens into the vagina.

The cervix itself features two openings: the internal os, which is the gateway from the uterine cavity into the cervical canal, and the external os, which opens into the vagina. These structures allow the passage of menstrual flow and provide an entry point for sperm while also protecting the uterine environment from external infections and facilitating childbirth.