Anatomy of urinary bladder and male urethra

1. Anatomy of urinary bladder and urehra
Dr. Mohamed Elfiky
Professor of anatomy and embryology

2. Urinary bladder
I- Site :
(a) At birth it lies in the abdominal cavity (due to the small size of the
pelvis).
(b) In children, it become a pelvi-abdominal organ.
(c) At puberty, it becomes a pelvic organ (due to enlargement of the pelvic
cavity ), where it occupies the most ant. compartment of the pelvis.
II- Size:
The mean capacity is 220 c.c, but it can accommodate up to 500 c.c.
without discomfort. As the bladder enlarges, it strips off the peritoneum
from the ant. Abdominal wall.
III- Shape:
It resembles a 4-sided pyramid (resembling a cut ant. part of a ship). The
full bladder is spherical in shape.
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3. It has 4 surfaces:
- Sup. surface.
- 2 infero-lateral surfaces.
- Post. surface (base).
It has 4 angles:
- Anterior angle (apex).
- Inferior angle (neck).
- 2 postero-superior angles behind.
4 ducts are related to the angles of the bladder:
- The 2 ureters open into the 2 postero-superior angles.
- The urethra comes out from the neck (inf. angle).
- The urachus (obliterated after birth to form median umbilical ligament) is
attached to the anterior angle (apex).
IV- Surfaces, Borders & Angles
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4. • The infero-lateral surfaces have the same relations in males & females.
• The sup. & post. surfaces have different relations in the 2 sexes.
(1) Relations of infero-lateral surfaces (common in male& female):
• Have no peritoneal covering.
• Related to the retropubic fat separating them from:
(a) Back of pubis.
(b) Obturator internus m., obturator nerve & vessels.
• (c) Levator ani.
(2) Apex (ant. angle): common in males & females. lies immediately behind the
upper border of the symphysis pubis & gives attachment to the median umbilical
liga.(Obliterated urachus).
(3) Anterior border : (the meeting of the 2 infero-lateral surfaces) common in males
& females : is related to the retropubic fat separating it from the symphysis pubis.
Relations of the urinary bladder
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5. (4) Relations of the superior surface in the male :
It is covered by peritoneum and related to coils of ileum & sigmoid
colon
(5) Relations of the post. surface (base) in the male:
Its upper part is covered by peritoneum.
It is related to the 2 seminal vesicles(Lat.) & 2 vasa deferentia ,
ampullae of vasa deferentia (Med.), separating it from the rectum.
(6) Relations of the neck in the male:
It lies 1/2 inch behind the lower part of the
symphysis pubis.
It rests on the prostate gland.
It gives out the urethra.
It gives attachment to the pubo-prostatic liga.
Relations of the urinary bladder
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6. (7) Relations of the superior surface in the female:
It is completely covered with peritoneum & related to the ant. (vesical)
surface of the uterus with the utero-vesical pouch in between(may contain
a loop of ileum).
(8) Relations of the of the post. Surface(base) in the female:
The base lies in direct contact with the upper part of anterior wall of the
vagina.
(9) Relations of the neck in the female:
It lies about 1/2 inch behind the lower part of symphysis pubis.
It rests on the pelvic fascia.
Gives attachment to the pubo-vesical ligament
Relations of the urinary bladder
Mohamed el fiky

7. Mohamed el fiky

8. The mucosa shows folds (rugae), except the trigone which is smooth.
The Trigone:
It is a triangular area on the inner aspect of post. bladder wall bounded by
3 lines joining the 2 ureteric orifices with the internal urethral orifice.
The mucosa of the trigone is smooth & tightly adherent to the underlying muscle coat.
It is richly supplied by nerves & blood vessels (appears more pink in colour).
Ureteric orifices: are 2 slit-like openings at the
postero-superior angles of the trigone lying 2.5 cm. apart in the empty bladder.
Inter-ureteric crest: is a transverse ridge between the 2 ureteric orifices.
The interior of the urinary bladder
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Uvula of the bladder: is a small elevation projecting upwards & is produced by the
median lobe of the prostate gland (its hypertrophy may lead to difficulty in
micturition= dysurea).
Internal urethral meatus: an opening situated at the most dependent part of the
bladder. It is surrounded by the sphincter vesicae which is an involuntary sphincter
supplied by autonomic nerves.

9. Trigone of bladder
ureteric orifice
Uvula of bladder
Male: coronal section Female: coronal section
The interior of the urinary bladder

10. (1) Median umbilical lig: from the apex of the bladder to the inner aspect of
the umbilicus. It represents the obliterated urachus.
(2) Lateral true ligament: from the side of the bladder to the tendinous arch
of the fascia covering obturator internus m.
(3) Posterior lig. : Extends from the lat edge of the base of the bladder to the
post. wall of the pelvis.
(4) Pubo-prostatic ligaments:
-They extends from the prostatic fascia to the back of pubis.
- In the female, they are replaced by the pubo-vesical
ligaments.
Ligaments of the urinary bladder
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11. Ligaments of the urinary bladder
Median umbilical lig
Lateral true ligament
Posterior lig.
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12. Autonomic fibres:
(1) Sympathetic : from (T.11,12 & L.1, 2)spinal segments
(inhibitory to the muscle wall & motor to the sphincter vesicae).
(2) Para-sympathetic: pelvic splanchnic n. (S. 2, 3, 4): motor
to the muscle wall & inhibitory to the sphincter vesicae.
Blood supply of the urinary bladder
Arterial supply:
(1) Superior vesical a.: from the proximal patent part of the obliterated umbilical artery.
(2) Inferior vesical a.: from the ant. division of int. iliac a.
Venous drainage : the vesical veins form a plexus on each infero-lateral surface, then drain
into the internal iliac vein.
Nerve supply
into external iliac lymph nodes.
Lymphatic drainage
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13. Male urethra
Shape : S-shaped
Length: 8 inch (20cm)
Extension: from the internal urethral
meatus at the neck of urinary bladder to
the external urethral meatus at the tip of
glans penis
Parts: 4 parts :
1. Pre-prostatic part
2. prostatic,
3. membranous
4. spongy
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14. is about 1 cm long, extends from the
base of the bladder to the prostate,
and is associated with a circular cuff
of smooth muscle fibers (the internal
urethral sphincter) . Contraction of
this sphincter prevents retrograde
move ment of semen into the bladder
during ejaculation.
The preprostatic part of the urethra
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15. Prostatic urethra
Site : passes vertically downwards through the prostate gland (From its base to its
apex)
Characters:
it is the widest & mast dilatable part of the whole urethra.it is about 3 cm long
The post. Wall of its lumen shows the following
features:
(a) urethral crest: a median longitudinal spindle shaped
elevation
(b) Seminal colliculus: a swelling on the middle of the urethral crest showing 3 openings:
- The opening of the prostatic utricle which is a small
diverticulum in the median plain of prostale gland
- The openings of the 2 ejaculatory duct (one on each side of the opening of the prostatic utricle).
(c) Prostatic sinus: a shallow groove around the urethral crest receiving the opening of prostatic glands.
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16. Membranous urethra
• Length : 2 cm long
Site: passes vertically downwards piercing 2 membranes (pelvic
• fascia & perineal membrane) i.e traversing the deep perineal
• pouch.
Relations: it is surrounded by the sphincter urethrae m. Characters: the
narrowest, shortest & least dilatable part of
• urethra.
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17. Spongy ( penile) urethraLength: 6 inches ( 15 cm ) long .
Site : It extends from the end of the membranous urethra to the external
• urethral meatus traversing the whole length of corpus spongiosum
Sphincter urthra
it is formed of 2 parts internal and external
• internal urthral sphincter : (sphincter vesicae ) : is a circular smooth muscle that surrounds the neck of the urinary bladder and internal urethral
orifice . it is involuntary and supplied by autonomic fibers .
• external sphincter urethrae(sphincter urethrae ) : formed of 2 parts :
• superior fibers : surround the bldder neck and has elements within the prostate .
• inferior fibers : are attached to the inner surface of inferior pubic ramus , they surround the membranous urethra .
Action of sphincter urethrae :
when the bladder contain urine , it compress the urthra .
during micturation : it relaxes . however , it contract to expel the last drops of urine or semen from the uretrhra .
Characters
• It has a dilatation at its beginning called intrabulbar fossa and other terminal dilatation called navicular fossa
• It receives the openins of the ducts of bulbo urethral glands N.B: the extenral urethral meatus is the narrowest point of urethra.
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18. Female urethra
• 1.5 inch long
• it corresponds to the prostatic
urethra of the male it descends
• from the internal urethral
meatus downwards,
embedded in the ant. wall of
the vagina to open into the
vestibule of the vagina below
& behind the clitoris by the
external urethral meatus
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