What is below the uterus?

The uterus is a unique organ in the human body. To put it simply, the uterus is the place where children are conceived after marriage. The fetus continues to grow in the woman's uterus and finally comes into the world. This means that women must protect their uterus in daily life and must not allow any problems to occur to the uterus. So, what is the part below a woman’s uterus? Let me give you a brief introduction.

Uterine shape and divisions

The uterus of an adult who is not pregnant is slightly flattened front and back, inverted pear-shaped, about 8 cm long, about 4 cm wide at its widest, and about 2 cm thick. The uterus can be divided into three parts: the round convex part above the cervical opening of the fallopian tubes on both sides is called the fundus of the uterus; the thin round part at the lower end is called the cervix; the part between the fundus and the cervix is ​​called the uterine body. The cervix is ​​divided into two parts: the part of the cervix that extends into the vagina is called the cervicovaginal part; the part above the vagina is called the upper cervicovaginal part. The part where the cervix connects to the uterine body is slightly narrow and is called the isthmus. During the non-pregnancy period, this part is not obvious and is about 1 cm long. During pregnancy, the isthmus of the uterus gradually expands and elongates (up to 7-11 cm), forming the lower uterine segment, where obstetricians often perform cesarean sections.

The inner cavity of the uterus is narrow and can be divided into upper and lower parts: the upper part is surrounded by the fundus and body, called the uterine cavity, and the lower part is inside the cervix, called the cervical canal. The uterine cavity is a triangular cavity that is slightly flattened front to back in the frontal position, with the base facing upward and the uterine openings of the fallopian tubes on both sides; the tip leads downward to the cervical canal. The cervical canal is prismatic, with its upper opening leading to the uterine cavity and its lower opening, called the cervical ostium, leading to the vagina.

The normal position of the uterus is mainly maintained by structures such as the uterine ligaments, pelvic diaphragm, urogenital diaphragm and perineal central tendon. When these structures are damaged or loose, uterine prolapse may occur.

1. Broad ligament of uterus:

The broad ligament of the uterus is a double-layer peritoneal fold on both sides of the uterus, extending from the peritoneum on the front and back of the uterus to the side wall of the pelvis. The upper edge of the broad ligament of the uterus is free, and contains the fallopian tube; the lower edge is attached to the pelvic floor, which can limit the displacement of the uterus to the sides.

(ii) Round ligament of uterus:

The round ligament of the uterus is a cord-like structure composed of smooth muscle and connective tissue. This ligament starts from the outer edge of the uterus, in front and below the cervical opening of the fallopian tube, between the two layers of peritoneum of the broad ligament of the uterus, runs forward along the side wall of the pelvis, passes through the inguinal canal to form a subcutaneous ring, and ends under the skin of the mons pubis and labia majora. This ligament is the main structure that maintains the anteverted position of the uterus.

(III) Cardinal ligament of the uterus:

The cardinal ligament of the uterus is composed of smooth muscle and connective tissue. It is located between the lower two layers of the broad ligament of the uterus, connecting from the upper part of the cervix and vagina to the side wall of the pelvis. It is the main structure that fixes the cervix and prevents the uterus from prolapsing downward.

(IV) Sacro-uterine ligament:

The sacrouterine ligament is composed of smooth muscle and connective tissue. It starts from the back of the upper part of the cervix and vagina, goes back around the rectum, and attaches to the front of the sacrum. This ligament has the function of pulling the cervix backward and upward, and together with the round ligament of the uterus maintains the anteversion and flexion position of the uterus.