Female Pelvis and Perineum Lecture
Female Pelvis and Perineum
Learning Objectives
Review of the female pelvic cavity
Understand anatomical aspects of the uterus, cervix, and vagina
Discuss the ligaments of the uterus and ovaries
Explore blood supply and innervation of female reproductive structures
Examine clinical correlations such as tubal ligation, hysterectomy, ectopic pregnancy, and variations in female anatomy
Female Pelvic Cavity Review
Structures of the Female Pelvic Cavity
Uterus: Contains three main parts:
Fundus: Upper third of the uterus
Body: Middle third of the uterus
Cervix: Inferior third of the uterus, positioned at the bottom
Cervix: Lower part that opens into the vagina, comprising about one third of the total uterine structure.
Vagina: Internal portion extending from the cervix down to the vaginal orifice.
Fallopian Tubes (Uterine Tubes): Lateral extensions from the uterus, functioning in oocyte transport.
Ovaries: Almond-shaped organs involved in gametogenesis and hormone production.
Terminology Distinction
Vagina: Internal structure.
Vulva: External parts of the female genitalia.
Peritoneal Reflections in Pelvis
Vesicouterine Pouch: Located between the bladder and uterus.
Rectouterine Pouch: Located between the rectum and uterus, notable as fluid accumulation site (cited in culdocentesis). Fluid can be extracted via aspiration through the posterior vaginal fornix.
Uterine Details
Uterine Position
Antiflexed and Anteverted: Normal positioning for most individuals assigned female. Fundus faces forward, while cervix points towards the posterior vaginal wall.
Retroflexed Uterus: Present in ~25% of individuals, where the uterus points backward.
Clinical Implication: Retroflexion can be associated with fertility issues, often temporary after labor.
Anatomical Angles
Angle of Version: Angle between the axis of the vaginal canal and axis of the cervix.
Angle of Flexion: Angle between the axis of the uterus and the cervix, often observed during physical examinations.
Uterine Size Changes
During pregnancy, the fundus reaches the costal margin, and the uterine walls thin significantly.
Postpartum, uterine size decreases rapidly; body may remain enlarged following multiple pregnancies.
Uterine Layers
Perimetrium: Serosa covering the uterus (including structures like the broad ligament).
Myometrium: Central smooth muscle layer, responsible for contractions.
Endometrium: Epithelial layer where embryo implants. It has two subdivisions:
Stratum Functionalis: Shed during menstruation.
Stratum Basalis: Retained throughout the menstrual cycle.
Uterine Tube Anatomy
Uterine Tube Structure
Infundibulum: Wide distal part with fimbriae (finger-like projections that guide oocytes).
Ampulla: Site where fertilization typically occurs.
Isthmus: Narrow proximal part of the tube.
Clinical Correlation
Hysterectomy Types:
Partial Hysterectomy: Preserves cervix, fallopian tubes, and ovaries.
Total Hysterectomy: Removes entire uterus and cervix.
Radical Hysterectomy: Removes uterus, cervix, fallopian tubes, and ovaries.
Tubal Ligation: Permanent birth control method; involves cutting, tying, or sealing fallopian tubes to prevent oocyte transport.
Ectopic Pregnancy
Definition: Implantation of a pregnancy outside the uterus, most often in the fallopian tube (97%).
Associated Risks: Can lead to internal hemorrhaging, infections, and increased risks if history of STIs, previous ectopic pregnancies, or pelvic surgeries.
Symptoms: Positive pregnancy test, pelvic pain, vaginal bleeding, gastrointestinal discomfort.
Treatment Options: Laparoscopic removal, salpingectomy, methotrexate.
Ovary Anatomy
Ovary Functions
Gametogenic: Produces ovarian follicles.
Endocrine: Secretes estrogens and progesterone.
Follicle Types
Primary Follicles: Small, early-stage follicles.
Graafian Follicles: Mature, large follicles ovulated approximately once per cycle.
Hormonal Regulation
Follicle Stimulating Hormone (FSH): Promotes follicular development.
Luteinizing Hormone (LH): Triggers ovulation and corpus luteum development.
Hormone peaks noted before ovulation with consequent rises in estrogen followed by progesterone during the luteal phase.
Ligaments of the Uterus and Ovaries
Types of Ligaments
Dense Connective Tissue: Round ligament of the uterus, ligament of the ovary, uterosacral ligament, transverse cervical ligament.
Peritoneal: Broad ligament divided into:
Mesometrium: Overlies the uterus.
Mesosalpinx: Covers the fallopian tube.
Mesovarium: Covers the ovary.
Cervix and Vagina
Cervical Anatomy
External os directed posteriorly, leading to the cervical canal.
Vaginal Portion: Part of the cervix protruding into the vaginal canal.
Supravaginal Portion: Above the vaginal fornix.
Cervical Changes During Menstrual Cycle
Firm and Closed: Before ovulation; becomes softer and opens as ovulation approaches.
Cervical Mucus Variations:
Thick and inhospitable during early follicular phase.
Thinner and conducive to sperm transport near ovulation.
IUDs: Copper IUDs act as spermicide; hormonal IUDs thicken cervical mucus to prevent entry of sperm.
Blood Supply to Reproductive Organs
Ovarian Supply:
Ovarian arteries: Branch directly from the abdominal aorta.
Ovarian drainage:
Left ovarian vein drains to the left renal vein; right ovarian vein drains directly to the inferior vena cava.
Uterine Supply:
Uterine artery branches from the internal iliac artery, with anastomoses to ovarian arteries near the uterine fundus for shared blood supply.
Vaginal Blood Supply: Typically received from the vaginal artery, branching from both the uterine and internal iliac arteries.
Clinical Correlation: Pelvic Congestion Syndrome
Description: Varicose veins in the pelvic cavity. Occurs mostly in women, often asymptomatic but may include pelvic pain, pain during intercourse, and increased urinary frequency.
Risk Factors: Multiple pregnancies, increased estrogen levels, prolonged standing/sitting.
External Genitalia
Structures:
Vulva: Includes labia majora, labia minora, clitoris, and vestibule.
Labia Minora: No fat or hair follicles; encloses the vestibule.
Labia Majora: Contains more adipose tissue and hair follicles.
Clitoris: Primarily a sensory organ with high concentrations of nerve endings (approximately 10,000).
Glands: Skene's (perineal) glands and Bartholin's glands provide lubrication, may become inflamed or infected.
Anatomical Variation: Significant variability in size, shape, and appearance of external genitalia among individuals.
Innervation of External Genitalia
Nerves: Dorsal nerve of the clitoris for sensory innervation, and pudendal nerve branches providing motor innervation to perineal muscles and sensation to the labia.
Lymphatic Drainage
Ovaries and upper parts of the uterus drain to lumbar nodes.
Body of the uterus and superior bladder drain to external iliac nodes.
Inferior parts of the bladder and cervix drain to internal iliac nodes.
Inferior vagina and rectum drain to sacral nodes.
Urinary System Review
Urinary Anatomy: The ureters travel from kidneys to the bladder, crossing the pelvic brim.
Ureter Relationships: Pass inferior to the uterine artery in females.
Bladder Anatomy: Comprised primarily of detrusor muscle; contains internal and external urethral sphincters for urine control.
Gender Affirming Surgeries
Transfeminine Surgeries:
Orchiectomy: Remove testes; simplifies hormone regulation.
Vaginoplasty: Constructs a vagina using existing tissues (typically penile inversion).
Transmasculine Surgeries:
Metoidioplasty: Form a neophallus from enlarged clitoral tissue, may allow urethral rerouting.
Phalloplasty: Create a neophallus using tissue from another body area (forearm, thigh).
Conclusion
Summary of anatomical structures, ligaments, blood supply, clinical correlations, and gender-affirming care.
Reminder for students to reach out with questions during office hours or via email.