Urogenital Organs

Urinary Bladder & Urethra - Bladder & Urethra Blueprint

• Urinary Bladder:
  • Hollow muscular organ; urothelium.
  • Parts: Apex, body, fundus, neck. Trigone: smooth.
  • Detrusor: Smooth muscle for micturition.
  • Capacity: 400-600 mL. Urge: 150-200 mL.
  • Innervation:
    • Parasympathetic (S2-S4): Micturition (contracts detrusor).
    • Sympathetic (T11-L2): Storage (relaxes detrusor).
    • Somatic (Pudendal n.): External sphincter (voluntary).
  • Arteries: Sup. & Inf. vesical aa. (internal iliac a.).
• Urethra:
  • Male Urethra (~20 cm):
    • Parts: Pre-prostatic, Prostatic (widest), Membranous (narrowest, ext. sphincter), Spongy (longest). (PPMMS)
    • 📌 Mnemonic: "Prostitutes Prefer Making Money Standing".
  • Female Urethra (~4 cm):
    • Shorter, anterior to vagina; ↑UTI risk.
    • Skene's glands (prostate homologue).

  ⭐ The membranous urethra in males is the narrowest and least distensible part, most prone to rupture during instrumentation.

Male Urogenital Organs - Gents' Gear & Ducts

• Testes & Epididymis
  • Testes: Paired oval glands in scrotum; produce sperm & testosterone. Tunica albuginea (fibrous capsule), septa divide into lobules containing seminiferous tubules.
  • Epididymis: Coiled tube on posterior testis; sperm maturation & storage. Head, body, tail (continuous with ductus deferens).
  • Blood Supply: Testicular artery (from aorta).
  • Innervation: Testicular plexus.
• Ductus (Vas) Deferens
  • Muscular tube; transports sperm from epididymis to ejaculatory duct.
  • Part of spermatic cord.
• Seminal Vesicles
  • Paired glands posterior to bladder; produce ~70% of seminal fluid (alkaline, fructose-rich).
  • Duct joins ductus deferens to form ejaculatory duct.
• Ejaculatory Ducts
  • Formed by union of ductus deferens & seminal vesicle duct; pass through prostate to empty into prostatic urethra.
• Prostate Gland
  • Walnut-sized gland inferior to bladder, surrounds prostatic urethra.
  • Produces ~25% of seminal fluid (milky, slightly acidic, contains PSA).
  • Zones: Peripheral (common site of cancer), central, transitional (BPH).

  ⭐ Clinical Pearl: The neurovascular bundles supplying the penis run posterolaterally to the prostate; crucial to preserve during prostatectomy to maintain erectile function.

• Bulbourethral (Cowper's) Glands
  • Pea-sized, posterolateral to membranous urethra; secrete pre-ejaculate (lubrication).
• Penis & Urethra
  • Penis: Corpora cavernosa (2, dorsal), corpus spongiosum (1, ventral, contains urethra).
  • Urethra: Prostatic, membranous, spongy (penile).

Female Urogenital Organs - Ladies' Layout & Lifeline

• Ovaries: Paired, in ovarian fossa.
  • Function: Oogenesis, hormone production (estrogen, progesterone).
  • Ligaments: Suspensory (vessels), Ovarian.
  • Blood: Ovarian a. (aorta); R vein to IVC, L vein to L renal v.
• Uterine Tubes (Fallopian): ~10 cm.
  • Parts: Infundibulum (fimbriae), Ampulla (fertilization), Isthmus, Intramural.
• Uterus: Pear-shaped.
  • Parts: Fundus, Body, Cervix. Layers: Peri-, Myo-, Endometrium (cyclic changes).
  • Position: Anteverted, anteflexed.
  • Supports: Broad lig., Round lig., Cardinal lig. (primary), Uterosacral lig.
  • Blood: Uterine a. (internal iliac a.).

  ⭐ Uterine artery crosses superior to ureter. 📌 "Water (ureter) under the bridge (uterine a.)".

• Vagina: Fibromuscular tube (~8-10 cm); cervix to vestibule. Fornices.
• Vulva: Mons pubis, Labia majora/minora, Clitoris, Vestibule (urethral/vaginal orifices, Bartholin's glands).
• Urethra: Short (~4 cm); opens in vestibule; prone to UTIs.

High‑Yield Points - ⚡ Biggest Takeaways

• Ureter is inferior to uterine artery ("water under bridge") near lateral vaginal fornix.
• Pudendal nerve (S2-S4): main motor/sensory supply to perineum.
• Membranous urethra: shortest, narrowest, least dilatable; prone to rupture.
• Micturition: parasympathetic (S2-S4) stimulates detrusor. Storage: sympathetic (T11-L2).
• Cardinal ligament: strongest support for uterus/cervix.
• Testicular/Ovarian arteries: arise from abdominal aorta (L2).
• Prostatic venous plexus drains to vertebral plexus (Batson's): metastasis route.