Chapter 75: Female Reproductive System Anatomy

Female Reproductive System Anatomy anatomical overview meticulously details the female reproductive system, structured into the lower genital tract, encompassing the vulva (pudendum) and vagina, and the upper tract, including the uterus, uterine tubes (Fallopian tubes), and ovaries. The external genitalia, or vulva, comprises structures like the clitoris (containing two corpora cavernosa), the labia majora (with subcutaneous layers analogous to Camper’s and Scarpa’s fasciae of the abdomen), the labia minora, and the vestibule of the vagina, which houses the external urethral and vaginal orifices, along with the greater vestibular glands (Bartholin’s glands), which are essential for lubrication. The vagina, a fibromuscular tube extending to the cervix, maintains a highly acidic environment (approximately pH 3) crucial for inhibiting microorganisms, achieved by Lactobacillus acidophilus breaking down glycogen; its proximal innervation is supplied by the pelvic splanchnic nerves while the distal part is supplied by the pudendal nerve. The mobile uterus sits between the bladder and rectum, typically exhibiting anteflexion and anteversion, and is robustly supported by connective tissue condensations known as ligaments, specifically the cardinal ligaments (of Mackenrodt) and the uterosacral ligaments, while the broad ligament is primarily a peritoneal reflection. The primary blood supply comes from the highly tortuous uterine artery, which branches from the internal iliac artery, giving off arcuate arteries and, crucially, the helicine arterioles that supply the endometrium. The endometrial lining undergoes cyclical changes during the menstrual cycle, comprising the proliferative phase (driven by estrogen), the secretory phase (driven by progesterone, characterized by glandular activity and lengthening of spiral arteries), and the subsequent menstrual phase where the functional layer is shed due to falling hormone levels. The uterine tubes consist of the isthmus, the ampulla (the typical site of fertilization), and the terminal fimbriae, which are key to capturing the oocyte. The ovaries, situated in the ovarian fossa and supported by the suspensory ligament of the ovary (containing the ovarian vessels originating from the abdominal aorta), house the developing follicles (e.g., secondary, antral, and preovulatory or Graafian follicle). Post-ovulation, the remnants form the hormone-secreting corpus luteum, which either degenerates into a corpus albicans if fertilization fails, or grows into a corpus luteum of pregnancy stimulated by human chorionic gonadotrophin (hCG). Pregnancy involves major uterine adaptation, including the formation of the thinner lower uterine segment from the isthmus and upper cervix, and risks such as placenta praevia (placenta covering the anatomical internal os) or the abnormal adherence conditions like placenta accreta, which profoundly influence the progression and safety of the three stages of labour.