Urinary Bladder, Prostate & Seminal Vesicles

Urinary Bladder

Basic Facts

  • Distensible urine reservoir.

  • Desire to void ≈ 300\;\text{ml}; maximum capacity ≈ 500\;\text{ml}.

External Features (Empty Bladder)

  • Four triangular surfaces

    • Posterior surface = base/fundus (broad above, pointed below).

    • Superior surface (faces upward; broad posteriorly; narrows anteriorly to form apex).

    • Right & left inferolateral surfaces (face downward, lateral & forward).

  • Apex: attached to lower end of median umbilical ligament (urachus).

  • Neck: lowest part; urethra emerges here;

    • Male—rests on prostate.

    • Female—rests on pelvic fascia.

  • Right & left lateral borders: junction of superior & inferolateral surfaces.

Relations – Male

  • Superior surface: separated by peritoneum from coils of ileum & sigmoid colon.

  • Inferolateral surfaces:

    • Anteriorly—retropubic (pre-vesical) fat pad between pubis / puboprostatic ligaments.

    • Posteriorly—fascia from levator ani & obturator internus.

  • Base: anterior to rectum; partly separated by seminal vesicles & ductus deferens.

  • Neck: directly on prostate.

Relations – Female

  • Superior surface: peritoneum separates bladder from uterus (body).

    • Reflected posteriorly onto uterine cervix → vesicouterine pouch.

  • Posterior part of superior surface: contacts upper cervix directly.

  • Inferolateral surfaces: same as male but puboprostatic → pubovesical ligaments.

  • Base: contacts anterior vaginal wall; no seminal vesicles.

Peritoneal Relations – Male

  • Superior surface covered by peritoneum.

  • Folds created:

    • Median umbilical fold (contains urachus/median umbilical ligament).

    • Lateral false ligaments (peritoneum reflected onto lateral pelvic wall).

    • Reflection posteriorly onto rectum forms rectovesical pouch (lowest male peritoneal recess).

    • Persisting fused layers below pouch = rectovesical (Denonvilliers’) fascia—limits posterior spread of prostatic carcinoma.

  • Inferolateral surfaces—non-peritoneal.

Peritoneal Relations – Female

  • Vesicouterine pouch between bladder & uterus; rectovaginal pouch behind uterus (rectouterine/Douglas).

Ligaments of the Bladder

  • TRUE (condensed fascia):

    • Median umbilical ligament (urachus) → apex → umbilicus.

    • Medial & lateral puboprostatic (male) / pubovesical (female) ligaments—thickened pelvic fascia over levator ani.

    • Lateral true ligament: pelvic fascia from bladder to obturator internus.

    • Posterior ligaments: fascia around vesical veins from base to internal iliac vein.

  • FALSE (peritoneal folds):

    • Median umbilical fold.

    • Right & left medial umbilical folds (obliterated distal umbilical arteries → medial umbilical ligaments).

    • Lateral false ligament (peritoneum from superior surface to side wall).

    • Sacrogenital folds: peritoneum from lateral base to sacrum—lateral walls of rectovesical pouch.

Internal Features

  • Mucosa folded when empty; smooth when full.

  • Trigone (smooth, non-folding mucosa on posterior wall):

    • Two ureteric orifices at upper angles.

    • Internal urethral orifice at inferior angle.

    • Interureteric crest connects ureteric orifices; forms upper boundary.

    • Uvula vesicae: slight bulge behind internal urethral orifice caused by median lobe of prostate.

Blood Supply

  • Arteries:

    • Superior vesical (ant. division internal iliac) – upper bladder.

    • Inferior vesical (males) or vaginal (females) – base & neck.

    • Additional twigs from obturator & inferior gluteal; uterine in females.

  • Veins: Vesical venous plexus on inferolateral surfaces → posterior ligaments → internal iliac veins.

  • Lymphatics: chiefly to external iliac nodes; some to internal/common iliac.

Nerve Supply (Vesical Plexus)

  • Parasympathetic: S2–S4 (nervi erigentes).

    • Motor to detrusor; inhibitory to internal sphincter.

    • Afferents—pain & distension awareness.

  • Sympathetic: T11–L2.

    • Motor to internal urethral sphincter (especially male bladder neck).

    • Role in ejaculation: contracts bladder neck preventing retrograde flow.

  • Pain pathway: mainly parasympathetic; ascends anterolateral columns—relief after bilateral cordotomy.

  • Distension/awareness fibres: posterior columns (fasciculus gracilis) → preserved post-cordotomy.

Applied Anatomy

  • Urinary incontinence: may follow pelvic floor damage (females), sphincter weakness, neurologic lesions.

  • Suprapubic (percutaneous) cystostomy feasible when bladder distended—peritoneum lifted off anterior wall.

  • BPH compresses urethra → obstructive symptoms; related to prostatic median lobe.

Male Urethra (Brief Context)

  • Four parts:

    1. Pre-prostatic \approx 1\;\text{cm}.

    2. Prostatic \approx 3\;\text{cm}.

    3. Membranous (through deep perineal pouch).

    4. Spongy/penile.

  • Two physiological bends when penis flaccid; straighten during catheterization.

Prostate Gland

Position & Shape

  • Inverted cone; base superior, apex inferior.

  • Situated below bladder neck, above pelvic diaphragm, behind pubic symphysis, anterior to rectum.

  • Dimensions: vertical 3\;\text{cm}, transverse 4\;\text{cm}, anteroposterior 2\;\text{cm}.

Capsules & Venous Plexus

  • True capsule: condensation of gland’s own fibrous stroma.

  • False capsule: visceral layer of pelvic fascia.

  • Between capsules lies prostatic venous plexus → drains to internal iliac veins & communicates with:

    • Deep dorsal vein of penis anteriorly.

    • Internal vertebral (Batson) plexus posteriorly → pathway for vertebral metastasis.

Lobes (Clinical Relevance)

  • Anterior (isthmus): fibromuscular, in front of urethra.

  • Posterior: behind urethra, below ejaculatory ducts; common carcinoma site.

  • Median (middle): between urethra & ejaculatory ducts; enlarges in BPH.

  • Right & left lateral lobes: beside urethra.

Surfaces & Relations

  • Base (superior): contiguous with bladder neck/internal urethral sphincter.

  • Apex (inferior): rests on superior fascia of urogenital diaphragm.

  • Posterior surface: against rectal ampulla (palpable in digital rectal exam).

  • Anterior surface: related to pubic symphysis via puboprostatic ligaments & retropubic space of Retzius.

  • Inferolateral surfaces: embraced by levator ani (levator prostatae fibers).

Ducts & Urethra

  • Prostatic urethra traverses gland; receives:

    • Right & left ejaculatory ducts (posterolateral to prostatic utricle on seminal colliculus).

    • 20–30 prostatic ducts opening into urethral sinus.

Blood, Lymph, Nerves

  • Arteries: Inferior vesical & middle rectal ("middle hemorrhoidal"); minor from internal pudendal.

  • Veins: prostatic plexus → internal iliac ± vertebral plexus.

  • Lymph: internal iliac & sacral nodes.

  • Nerves: inferior hypogastric plexus (symp + parasymp); prostatic plexus intimately associated—important in erectile function.

Applied / Examination

  • Digital rectal exam assesses posterior lobe: size, consistency, nodularity.

  • TURP/BPH surgery endangers prostatic venous plexus → hemorrhage.

  • Carcinoma spreads via veins to vertebrae & skull.

  • Peritoneal relation: prostate is entirely extraperitoneal; separated from rectum by Denonvilliers’ fascia.

Seminal Vesicles

Structure & Position

  • Paired, lobulated, posterior to bladder base, anterior to rectum, lateral to vas deferens ampulla.

  • Each: single convoluted tube \approx 5\;\text{cm} folded to \approx 2\;\text{cm} mass; superior end blind; inferior end forms duct.

  • Duct + ipsilateral ductus deferens → ejaculatory duct traversing prostate to open on seminal colliculus.

Function

  • Secretes alkaline, fructose-rich fluid (energy source for sperm).

  • Does NOT store sperm.

Vascular & Lymphatics

  • Arteries: inferior vesical & middle rectal (internal pudendal) branches.

  • Veins: to internal iliac vein.

  • Lymph: internal iliac nodes.

Clinical Notes

  • Palpable superior to prostate on rectal exam when enlarged.

  • Calcification visible on imaging may mimic stones.

Comparative Blood / Lymph (Prostate vs. Seminal Vesicle)

  • Arterial:

    • Prostate → inferior vesical + middle rectal ± internal pudendal.

    • Seminal vesicle → inferior vesical + middle rectal.

  • Venous: both drain to internal iliac via vesical/prostatic plexus.

  • Lymph: prostate → internal iliac & sacral; seminal vesicle → internal iliac.

Management Principles (Brief)

  • Urinary incontinence: treat causative factor; pelvic floor exercises, pharmacotherapy (antimuscarinics, β-3 agonists), surgical slings/TVT; catheterization if neurogenic.

  • BPH: α-1 blockers, 5-α reductase inhibitors, minimally invasive procedures (TURP, laser), watchful waiting; monitor PSA to differentiate from cancer.

Quick Revision Points

  • Median lobe → BPH; posterior lobe → carcinoma.

  • Denonvilliers’ fascia blocks direct rectal invasion by prostatic cancer.

  • True vs. false ligaments distinguished by fascia vs. peritoneum.

  • Arterial supply of bladder: superior & inferior vesical (internal iliac) ± obturator, inf gluteal, uterine/vaginal.

  • Male vs. female bladder relations: prostate vs. vagina; puboprostatic vs. pubovesical ligaments; rectovesical vs. vesicouterine + rectovaginal peritoneal pouches.