Anatomy of Lower Urinary Tract

1
Anatomy of Lower Urinary Tract

• Hann-Chorng Kuo
• Department of Urology
• Buddhist Tzu Chi General Hospital

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Embryology of Lower Urinary Tract

• Cloaca
• Procodeum- ectodermal depression in hindgut
• Cloacal membrane
• Cloaca separates to urogenital sinus and rectum
• Bladder proper hallow muscular organ
• Detrusor and urethral muscles have the same origin

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Embryology of Lower Urinary Tract
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Development of Urogenital Ductsin an 8-week old
fetus
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Development of Prostate and Female Genital Organs
(12 weeks)
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Embryology of Genital Tract

• Mesonephric duct ejaculatory duct
• Fused Mullerian duct prostate and membranous
  urethra (M), whole urethra (F)
• Fused Mullerian duct upper 2/3 of vagina,
  uterus, fallopian tubes (F)

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The Urinary Bladder

• A hallow muscular organ
• Anterior wall behind pubic symphysis
• Apex median umblical ligament umbilicus
• Dome peritoneal covering
• Posterior wall trigone and ureteral orifices
• Bladder neck - urethra

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Sonography of Urinary Bladder
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Cystography of Urinary Bladder
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Structure of the Bladder

• Epithelial lining transitional cell
• Loose submucosal connective tissue
• Muscular wall
• Serosal layer

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Cystoscopy of Urinary Bladder
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The Detrusor

• Widely separated coarse muscle bundles
• No definite orientation
• Tree definite layers at the bladder neck
• Longitudinal muscles fused to deep trigone and
  penetrate base of prostate gland
• Muscle fibers wrap around the urethra and return
  to the bladder

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Bladder Musculature in Cystoscopy
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Anatomy of Bladder in Image Study

• Smooth wall, well distended, smooth base
• Trabeculation in bladder outlet obstruction
• Bladder neck incompetence in stress incontinence
• Cystocele in pelvic floor weakness
• Bladder base elevation in prostatic enlargement
• No vesico-ureteral reflux

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Bladder Trabeculation in Cystogram
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Stress Urinary Incontinence
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Cystocele
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Prostate Enlargement and Bladder Base Indentation
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Blood Supply of the Bladder

• Arterial supply superior, middle,inferior
  vesical arteries branched from hypogastric artery
• Also from inferior gluteal, obturator, uterine
  and vaginal ateries
• Venous drainage hypogastric veins
• Communicating with retropubic venous plexus or
  Santorini plexus

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Neuroanatomy of Bladder

• Sympathetic nerves T11-T12, L1- L2
• Sympathetic trunk- lumbar splanchic nerves
  hypogastric plexus- pelvic plexus- trigone, lower
  end of ureter, bladder neck
• Parasympathetic nerves S2-S4
• Pelvic parasympathetic plexus- hypogastric plexus
  vesical branches detrusor
• Sensory pathways sympathetic (pain,touch,
  temperature) and parasympathetic nerves (stretch,
  fullness)

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Neuroanatomy of Urinary Bladder
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The Ureterovesical junction

• Comprise (1) lower ureter, (2) trigone, (3)
  adjacent bladder wall
• Waldeyers sheath- juxtavesical ureter
• Intravesical ureter intramural segment and
  submucosal segment
• Ureteral muscle fiber continue to the trigone and
  extend to the bladder neck

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Anatomy of Vesicoureteral Junction
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The Trigone

• Superficial trigone
• Continuous extension of longitudinal ureteral
  fibers to bladder base and proceed to urethra
• Deep trigone
• Fibers of Waldeyers sheath continue downward
  to bladder base
• Two trigone layers continue with the lower ureter

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Function of Vesicoureteral Junction

• Free efflux of urine from ureter to bladder
• Prevent reflux of urine from bladder to ureter
• As bladder is filled,the trigone is stretched
• Increased resistance of the intravesical ureter
• During detrusor contraction, trigone contracts
  concomitantly, completely sealing ureter against
  efflux and reflux

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Vesicoureteral reflux during Voiding Phase
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Vesicoureteral Reflux and Pseudodyssynergia in
Child
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Grades of Vesicoureteral Reflux
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Appearance of Uretreral Orifice
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The Bladder Neck

• The trigonal musculature- superficial layer
  continue with ureteral muscle, deep layer
  continue with Waldeyers sheath
• Detrusor distributes into three layers inner
  longitudinal, middle circular, outer longitudinal
  m.
• Bladder neck opens during voiding and closed
  during ejaculation

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Cystoscopy of Bladder Neck
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Sonography of Bladder Neck
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Bladder Neck Incompetence in Urgency- Frequency
and SUI
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The Female Urethra

• A 4-cm muscular tube in females
• Inner longitudinal and outer circular musculature
• Both muscles are connecting with the detrusor
• Surrounded by striated skeletal muscle external
  sphincter, in an omega shape
• Pelvic floor muscles

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Cystoscopy of Female Urethra
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Sonography of Female Urethra
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Relationship of Urethra and Pelvic Floor Muscles
Endopelvic Fascia
Bladder
Smooth muscle
Striated
Symphysis pubis
Striated muscle
Smooth muscle
Urethropelvic ligament
Smooth muscle
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Relationship of Urethra and External Urethral
Sphincter
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The Male Urethra

• Striated external sphincter bulk around
  membranous urethra and extend over apex of
  prostate, especially anteriorly
• Contains slow twitch (35)-sustained tonus, fast
  twitch fatigable fibers (50), and fast twitch
  fatigue resistant (15)- for emergency
• External sphincter is about 1 inch long and 6 mm
  deep

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Cystoscopy of Male Urethra
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Benign Prostate Enlargement
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Transrectal Sonography of Male Urethra and
Prostate
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Anatomy of Male Urethra and Adjacent Organs
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Sonography of Prostate Enlargement
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Transrectal Sonography of ProstateProstatic
Transition Zone
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The Male Urethra

• Prostate urethra, Membranous urethra, Bulbous
  urethra, Penile urethra, Urethral meatus

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Urethral Pressure Profile in Male
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The Female Urethra

• Mucosa is transitional epithelium, becoming
  stratified squamous toward meatus
• Submucosa is very vascular
• Innervated by parasympathetic cholinergic fibers
  and sympathetic alpha-adrenergic fibers
• Abundant nitric oxide synthase in smooth muscle
  and striated muscles

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Urethral Pressure Profile in Women
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Cross Section of Female Urethra
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Nitric Oxide Donor Urethral Pressure Profilometry
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Bladder Outlet Obstruction in Female Urethra