Endometrium and Menstrual Cycle Overview

Endometrium

• Innermost layer of the uterus that responds to hormonal changes throughout the menstrual cycle and during pregnancy.
• Composed of two layers:
  • Glandular Layer: sheds during menstruation, thickens during the proliferative and secretory phases.
  • Basal Layer: adjacent to the myometrium, regenerates new endometrium after menstruation and delivery.

Uterine Anomalies

• Class V: Septated uterus (presence of uterine septum or partition).
• Class VI: DES uterus, characterized by a "T-shaped" uterine cavity due to fetal exposure to diethylstilbestrol.

Uterine Ligaments

• Broad Ligament: Supports sides of the uterus, maintains anteversion and anteflexion positions.
• Cardinal Ligament: Main support for the uterus; damage may lead to uterine prolapse.
• Uterosacral Ligament: Connects the uterus to the sacrum.
• Anterior Ligament: Supports uterus in relation to bladder; overstretching can cause cystocele (bladder herniation).
• Posterior Ligament: Forms the cul-de-sac of Douglas; damage may lead to rectocele (rectum herniation).

Fallopian Tubes

• Two slender muscular tubes extending from upper corners of the uterine body; main site for fertilization of ova by sperm.
• Parts include:
  • Interstitial: smallest lumen, lies within uterine wall (1 cm).
  • Isthmus: portion commonly cut during tubal ligation (2 cm).
  • Ampulla: longest part (5 cm), exact site of fertilization (outer third).
  • Infundibulum: most distal portion with fimbriae that help guide ova into tubes.

Uterus Divisions

• Cervix: Lower portion of the uterus, includes:
  • External Cervical Os: distal opening to the vagina.
  • Cervical Canal: cavity within the cervix.
  • Internal Cervical Os: opening to the uterus.
• Fundus: Uppermost convex portion, palpated for uterine growth during pregnancy, and assesses labor contractions.
• Isthmus: Constricted portion above the cervix, incised during cesarean section.
• Corpus: Main body of the uterus, housing the fetus during pregnancy.
• Cornua: Upper portions where the fallopian tubes attach.

Uterine Layers

• Perimetrium: Outermost layer attached to broad ligaments; adds support.
• Myometrium: Middle muscular layer; expels the fetus during birth and contracts around blood vessels to prevent hemorrhage.

Vaginal Structure

• Vaginal Orifice: External vaginal opening, covered by hymen in virgins; flanking Bartholin's glands provide lubrication.
• Grafenberg Spot: Sensitive area at the inner anterior aspect of the vagina.
• Fourchette: Tissue fold formed by merging labia majora and minora below the vaginal opening.

Internal Structures

• Vagina: Hollow, muscular canal measuring 3-4 inches, features rugae for stretching. Functions include menstruation passage, fetal passage, and organ of copulation.
• Doderlein’s Bacillus: Maintains normal vaginal flora, creating an acidic pH (4-5) that inhibits pathogenic bacteria.
• Fornices: Four recesses around the cervix formed by its projection into the vaginal canal.

Uterus Overview

• Hollow, muscular, pear-shaped organ located in the pelvis, weighing 50-60 g in non-pregnant women.
• Maintained in position by broad ligaments and receives abundant blood supply from uterine and ovarian arteries.

Explore the intricate structure and functions of the endometrium, the innermost layer of the uterus. This quiz covers its changes during the menstrual cycle, the differences between the glandular and basal layers, and various uterine anomalies. Test your knowledge on how hormonal responses affect uterine health and processes.