Uterine Anatomy and Function

Overview of the Uterus

  • The uterus plays a critical role in female reproduction, primarily responsible for carrying the conceptus (the fertilized egg or zygote) to term.

Gross Anatomy of the Uterus

  • It consists of the following main structures:

    • Uterine tubes (fallopian tubes)

    • Paired tubes that open into the fundus of the uterus.

    • Body of the uterus.

    • Cervix

    • Extends down and opens into the vaginal canal.

Shape and Structure

  • The uterus is described as pear-shaped, specifically an inverted pear.

Uterine Tubes Structure

  • Each uterine tube has three parts:

    1. Infundibulum

    • Funnel-like structure that opens into the abdominal cavity with finger-like projections called fimbriae.

    1. Ampulla

    • Most important part for fertilization, where the egg is typically fertilized.

    1. Isthmus

    • Tapered part that opens into the body of the uterus.

Cervical Anatomy

  • The cervix has two openings:

    • External os

    • Opening from the vaginal canal into the cervix.

    • Internal os

    • Opening from the cervix into the uterus.

Fornices

  • Fornices

    • Recesses around the cervix divided into:

    • Anterior fornix

    • Posterior fornix

    • Lateral fornices

Uterine Wall Structure

  • Three layers of the uterine wall:

    1. Perimetrium

    • Outermost layer, composed of simple squamous epithelium, providing a slippery surface for organ movement.

    1. Myometrium

    • Thick, muscular middle layer made up of smooth muscle cells, responsible for uterine contractions.

    1. Endometrium

    • Innermost layer composed of two sub-layers:

      • Basal layer

        • Consistent, permanent layer that remains throughout the menstrual cycle.

      • Functional layer

        • Glandular epithelium that proliferates, thickens, and gets sloughed off if implantation does not occur.

        • Rich in glycogen and blood supply, conducive to embryo implantation during the proliferative phase of the menstrual cycle.

Phases of the Menstrual Cycle

  • The functional layer undergoes several changes:

    • Builds up during the proliferative phase.

    • Is shed off during the menstrual phase if no embryo is implanted.

Vascular Supply to the Uterus

  • Blood supply originates from the abdominal aorta, which divides into:

    • Common iliac arteries, further dividing into internal and external iliac arteries.

  • The internal iliac artery has an anterior branch, which gives rise to the uterine artery:

    • Paired uterine arteries approach the uterus and give off:

    • Arcuate arteries

      • Arc around the uterus's perimeter.

    • Radial or Radiate arteries

      • Penetrate into the uterine tissue.

    • Spiral arteries

      • Penetrate into the functional layer, undergo angiogenesis during growth phases.

Blood Supply

  • Layers of blood supply:

    • Spiral arteries

    • Straight arteries

    • Some references vary in including straight arteries.

    • Basal arteries

    • Supplying basal cells and remain constant.

Importance of Ovarian Blood Supply

  • Gonadal arteries from the abdominal aorta provide primary blood supply to the ovaries:

    • Uterine artery also provides an additional branch:

    • Ovarian branch supplies blood to the ovary, part of the broad ligament.

  • Risk of ovarian tissue dying if gonadal arteries become compressed or damaged.

Conclusion of Uterine Anatomy

  • Covered the anatomy of the uterus, the structures surrounding it, the layers of the uterine wall, and detailed blood supply to both the uterus and ovaries.

  • The uterine and ovarian blood supply is crucial for the health and functionality of the reproductive system, illustrating the interconnectedness of these organs in female reproduction management.