Uterus

Cross-section of human uterus.

The uterus, commonly referred to as the womb, is a pivotal component of the reproductive system in the female body. It serves as the nurturing ground where a fetus develops over the course of roughly nine months during pregnancy. Shaped reminiscently of a pear, this organ is strategically situated posterior to the bladder and anterior to the rectum. In non-pregnant conditions, the uterus weighs around 70 grams. A distinctive feature of the uterus is the endometrium, which is periodically shed resulting in the menstrual flow (menstruation) in cyclic intervals, averaging 28 days for most women, though this duration can vary individually. Upon fertilization, an egg migrates via the fallopian tube and finds its anchoring spot in the endometrium.

Anatomy

Positioned as a core structure within the female reproductive system, the uterus has its existence complemented by the vagina, ovaries, and fallopian tubes. Breaking down its anatomy, the uterus is demarcated into four main regions:

• The fundus, which forms the rounded top.
• The central body of the uterus.
• The uterotubal angles that seamlessly connect to the fallopian tubes.
• And the base, known as the cervix.

In terms of layering:

The outermost layer is named the perimetrium or alternatively, the serosa. This slender lining encapsulates the uterus and primarily consists of epithelial cell tissue. The robust middle layer, myometrium, constitutes the bulk of the uterine structure. blood vessels play a pivotal role in supplying nutrients to the uterus. While arteries like the internal iliac, ovarian, and uterine arteries ensure a steady flow of blood to the uterine layers, veins are responsible for the return journey to the heart and lungs.

An intricate ligamentary system, including the anterior, posterior, lateral, uterosacral, and round ligaments, holds the uterus securely in position. Notably, the relative positioning of the uterus can fluctuate depending on the bladder's content.

Throughout a woman's lifespan, the uterus undergoes various phases. From dormancy during childhood and senescence, to heightened activity during reproductive years, the uterus is integral for menstruation, fetal development, and childbirth.

Tumors

Though infrequent, the uterus can be susceptible to cancers, the prominent ones being endometrial cancer and uterine sarcoma. While endometrial cancer arises from the endometrial lining cells, uterine sarcoma, albeit rare, originates from the smooth muscle cells.

Abnormal uterus

The uterus undergoes significant enlargement during pregnancy

Congenital abnormalities can sometimes result in an atypical uterine structure. Such conditions might be accompanied by anomalies in other organs too.

Pregnancy

With the onset of pregnancy, the uterus undergoes dramatic transformations. From accommodating the growing fetus to housing the placenta and amniotic fluid, its volume can expand to hold five to twenty liters. Predominantly, the uterus comprises smooth muscle, the myometrium, which exhibits cellular proliferation during pregnancy. As pregnancy advances, the outer myometrium thickens, while the inner layer becomes comparably thinner, allowing healthcare practitioners to palpate the fetus.

Uterine prolapse

In certain situations, the uterus can descend, becoming visible through the vagina. This phenomenon, more prevalent in older women, can be attributed to:

• Aging
• Diminished estrogen post-menopause
• Obesity
• Chronic coughing
• Tumors
• Excessive strain during bowel movements
• Weakened pelvic muscles

See Also

Menstruation Pregnancy Human reproductive system

References

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