Anatomy of the Uterus

The uterus is a female reproductive system organ where the growth of the baby takes place. It is also referred to as the womb. The uterus is structurally hollow and pear-shaped with almost a fist size. The uterus is connected to the fallopian tube assisting in the translocation of eggs from the ovary into the uterus. On the other hand, the uterus lower parts form the cervix that connects to the vagina. At the same time, the upper part of the uterus is more expansive and forms the corpus. Subsequently, the uterus is divided into three layers known as endometrium, myometrium, and serosa.1

Also, the uterus comprises four sections: the upper area, which is broadly curved, is known as the Fondus. It is within this region that the fallopian tube connects to the uterus. Another section is the body which is the largest part of the uterus. The body begins directly below the fallopian tube and extends downwards until the cavity and uterine walls narrow.

Also is the isthmus, which is the narrow lower neck region. Finally, is the cervix that also continuous downwards until it opens into the vagina. The uterus size is approximated to be 6 to 8 cm long. In comparison, the thickness of the walls is estimated to be 2 to 3 cm. the width of the organ is approximated to 6cm but usually varies.2

The outer layer of the Uterus (Peritoneum membrane) partially covers the organ. In front, Peritoneum covers the cervix body only. While from behind, it covers the cervixs parts and body that lies above the vagina and is extended to the posterior vaginal walls, after which it is folded back to the rectum.

Also, from the sides, peritoneal layers extend from the uterus margin to each sidewall of the pelvis resulting in two broad ligaments of the uterus. The myometrium, composed of the larger part of the organs bulkiness, is firm and has unstriped, densely packed, and smooth muscle fibers. Also present are the blood vessels, nerves, and lymph vessels. The outermost fibers are longitudinally arranged, while the middle layer has no pattern of arrangement, thus, running in all directions in a disorderly manner. The middle layer being the thickest.3

The uterine lining cavity forms the endometrium, which is a moist mucous membrane. Usually, when an egg is released into the fallopian tube, the endometrium of the uterus thickens to receive a fertilized egg. The thickness of the lining varies during the menstrual cycle. The lining thickens during the egg release in preparation for implantation. When the egg is fertilized, it gets attached to the endometrium walls to start development. However, an unfertilized egg leaves the uterus through the vagina while the endometrium lining is shed during the menstrual period.

Furthermore, the sperms and eggs are kept alive by secretions produced by the endometrium. The endometrium fluid contains potassium, water, glucose, iron, chloride, proteins, and sodium. Glucose acts as the reproductive cells nutrients while proteins aid in the implantation of the fertilized egg. At the same time, the other constituents avail a conducive environment for the sperm cells and the egg.5

In addition, the uterine wall is composed of three-layered muscle tissue. The muscle fibers move obliquely, longitudinally, and circularly entwined...…while parasympathetic supply is derived from S2 to S4.2 Nonetheless, the cervix and the uterus are not sensitive to burning or cutting, enabling cauterization of the cervix without anesthesia while carrying out inportant therapeutic procedures. On the contrary, the cervix and uterus are sensitive to dilation and distension; thus, the reason for the pain experienced during normal delivery.4

The uterus lymphatic drainage is done through the sacral, iliac, inguinal, and aortic lymph nodes. The uterus fundal parts mainly drain into para-aortic lymph nodes, the fallopian tube, and the ovarian lymphatic drainage. Other parts of it also drain into superficial inguinal lymph nodes beside the round ligament. The uterus lower parts drain along uterine blood vessels into internal and external iliac lymph nodes.2

The uterus earlier development is very complex. In around two months of gestation, both the male and females primordia mesonephric and internal genitalia paramesonephric ducts appear. The processes of sexual differentiation go through multiple steps that take place due to several factors including hormonal signals, growth factors, and inherited genetic influences.1

Accordingly, paramesonephric ducts of the two sides project caudally until they get to the urogenital sinus, from where they extend to its posterior wall to form the Mullerian tubercle. The fallopian tube is then formed from the initial two parts of Mullerian ducts. The third portion is fused with its counterparts to canalize and form the cervix, upper fifth of the vagina, and uterus.

Some of the developmental variants may occur when the long cervix axis is not in line with the uterus body long axis as it commonly happens. Usually, the uterus body long axis is tilted over the cervixs long axis,…