1. Gross Anatomy of Urinary System –II
Urinary Bladder, Urethra
Dr. Prabhakar Yadav
Assistant Professor
Department of Human Anatomy
B.P. Koirala Institute of Health Sciences

2. URINARY BLADDER
Muscular reservoir of urine
Location: Anterior part of pelvic cavity immediately behind the pubic symphysis &
in front of rectum in male and uterus in female.
• When empty - within the lesser pelvis
• when distended, it expands upward & forward into the abdominal cavity.

3. Detrusor muscle: is arranged in whorls and spirals - adapted for mass contraction
rather than peristalsis.
Shape
when empty: tetrahedral
when distended: ovoid
Capacity
• Normally in adult 120 to 320 ml.
Mean capacity- 220 ml.
• 220 ml ---- desire to micturate
• bladder is usually emptied at about 250–300 ml.

4. EXTERNAL FEATURES:
a) Apex- directed forwards
b) Base or fundus- directed backwards
C) Neck- lowest & most fixed part of
bladder
D)Three surfaces: superior, right & left
inferolateral
e) Four borders: two lateral, one
anterior and one posterior

5. Relations
1. Apex is connected to the umbilicus by the
median umbilical ligament {obliterated intra-
abdominal part of the allantois (urachus)}

6. 2. Base:
(a) In female - related to uterine cervix &
vagina
b) In male--
Upper part of base is separated from rectum
by retrovesical pouch
Lower part is separated from rectum by
seminal vesicles & terminations of vas
deferens.
Triangular area between two deferent ducts is
separated from rectum by rectovesical fascia of
Denonvilliers

7. NECK:
Lies 3–4 cm behind the lower part of pubic
symphysis & is pierced by the urethra
It is situated where inferolateral surface &
posterior surfaces(Base) of the bladder meet.
In male, neck rests on upper surface of prostate
In female, it is related to urogenital diaphragm.

8. SUPERIOR SURFACE:
Male:
Completely covered by
peritoneum which separates it
from coils of ileum, and/or
sigmoid colon.
Female:
covered by peritoneum except for
small area near the posterior
border, which is related to
supravaginal part of uterine cervix.
peritoneum is reflected on to the
uterine isthmus forming
vesicouterine pouch.

9. Inferolateral surfaces are devoid of peritoneum & in both male and female are related:
In front to:
– pubic symphysis,
– retropubic space,
– puboprostatic ligaments.(Pubovesical ligament)
Behind to :
– obturator internus muscle above,
and
– levator ani muscle below.

10. As the bladder fills,
Inferolateral surfaces - anterior
surface
It is covered by peritoneum
only in its upper part.
Lower part comes into direct
contact with anterior
abdominal wall. - Suprapubic
catheterization

12. SUPPORTS OF THE URINARY BLADDER
True Ligaments
- formed by condensation of pelvic
fascia around the neck & base of the
bladder & are continuous with the
fascia on the superior surface of
levator ani.
1. Lateral ligaments (right and left):
extend from the side (inferolateral
surface) to the tendinous arch of
pelvic fascia.

13. 2. Puboprostatic ligaments:
fix the neck of bladder.
(a) Lateral puboprostatic ligament.
• directed medially and backwards.
• extends from the anterior end of
the tendinous arch of the pelvic
fascia to the upper part of the
prostatic sheath
(b) Medial puboprostatic ligament.
• directed downwards and backwards.
• extends from the back of the pubic
bone (near the pubic symphysis) to
the prostatic sheath.
• Ligaments of the two sides form the
floor of the retropubic space
In females, bands similar to the puboprostatic
ligaments are known as the pubovesical
ligaments which end around the neck of the
bladder

14. 3. Posterior ligament ( right and left):
• directed backwards and upwards
• extend on each side from base of
the bladder to the lateral pelvic
wall.
• Enclose the vesical venous plexus.
4. Median umbilical ligament:
• is fibrous remnant of urachus.
• extends from the apex of bladder
to umbilicus.

15. False Ligaments
are peritoneal folds ; do not have supportive
function; are seven in number
Anteriorly - three folds:
• Median umbilical fold: fold of peritoneum
over the median umbilical ligament.
• Two medial umbilical folds: folds of
peritoneum over obliterated umbilical
arteries.
Laterally
• Two lateral false ligaments, reflection of the
peritoneum of paravesical fossae from the
bladder to the side wall of the pelvis
Posteriorly
• two posterior false ligaments, sacrogenital
folds of peritoneum extending from the side
of the bladder, posteriorly, to the anterior
aspect of the third sacral vertebra.

16. INTERIOR OF THE BLADDER:
Rugae:
Trigone of the bladder:
Features of Triagone:
1.Anteroinferior angle- internal orifice of the
urethra.
2. Two posterosuperior angles- openings of
the ureters.
3. Uvula vesicae- a slight elevation in the
mucous membrane immediately above &
behind the internal urethral orifice.
• produced by median lobe of prostate.
4.Interureteric ridge/crest or bar of Mercier:
• forms the base of the trigone
• produced by the continuation of inner
longitudional muscle coats of 2 ureters
Lateral ends of the ridge extend beyond the
openings of the ureter as ureteric folds
Interureteric ridge (bar of Mercier) serves as a
guide to locate the orifices of the ureter
during cystoscopy.

17. ARTERIAL SUPPLY:
Superior & Inferior vesical arteries
branches of anterior division of internal iliac arteries
lower part of the bladder are:
(a) Obturator and inferior gluteal arteries.
(b) Uterine and vaginal arteries in the female
VENOUS DRAINAGE
veins of the bladder do not follow the arteries.
on inferolateral surfaces of the bladder veins form
vesical venous plexus.
Veins from this plexus pass backwards in the
posterior ligaments of the bladder, and drain into
the internal iliac veins.

18. Lymphatic Drainage
Mostly to external iliac nodes.
Few vessels to the internal iliac nodes or to the
lateral aortic nodes.

19. Nerve supply:
Supplied by the vesical plexus -derived from
the inferior hypogastric plexus.
The vesical plexus contains both sympathetic
and parasympathetic components, & each
contains motor and sensory fibres.
Parasympathetic efferent fibres or nervi eri-
gentes, S2, S3, S4 are motor to the detrusor
muscle and inhibitory to the sphincter vesicae
(internal urethral sphincter).
Sympathetic efferent fibres (T1 1 to L2) are
inhibitory to the detrusor and motor to the
sphincter vesicae
somatic, pudendal nerve (S2, S3, S4) supplies
the sphincter urethrae (external
urethral sphincter) which is voluntary.
Sensory Innervation
Pain sensations, are carried mainly by
parasympathetic nerves and partly by
sympathetic nerves .

20. Micturation is a reflex function, involving
the motor and sensory pathways.
Acute injury to cervical/thoracic segments
of spinal cord leads to a state of spinal
shock.
Muscle of bladder is relaxed, sphincter
vesicae contracted, but sphincter urethrae
relaxed. Bladder distends& urine dribbles.
After a few days, bladder starts contracting
reflexly. When it is full, it contracts every 2-
4 hours. This is Automatic reflex bladder
Damage to the sacral segments of spinal
cord results in “Autonomous bladder". The
bladder wall is flaccid and its capacity is
greatly increased. It just fills to capacity and
overflows. So there is continuous dribbling.

21. Urethra
MALE URETHRA :
• is a membranous canal for external
discharge of urine & seminal fluid.
• 18 to 20 cm long
• extends from the internal urethral orifice
to the external urethral orifice
• In flaccid state of the penis, the long axis
of the urethra presents two curvatures
and is therefore S-shaped.
• In erect state of the penis, the distal
curvature disappears becomes ‘J-shaped’.

22. PARTS:
1. Prostatic part (passes through prostate):3 Cm
2. Membranous part (passes through urogenital
diaphragm):1.5 to 2 Cm
3. Spongy or penile part (passes through bulb &
corpus spongiosum of penis):15 Cm
Prostatic Part :
begins at internal urethral orifice & runs vertically
downwards through the anterior part of prostate .
widest and most dilatable part of male urethra.
widest in its middle & narrowest where it joins
the membranous urethra.

23. 1.urethral crest or veru-montanum is a median
longitudinal ridge of mucous membrane
2. colliculus seminalis: Elevation on the middle of
urethral crest.
• On colliculus seminalis there is opening of
prostatic utricle.
• On each side of opening of prostatic utricle
there are openings of the ejaculatory ducts.
3. Prostatic sinuses are two vertical grooves
situated one on each side of urethral crest
containing openings of about 20 to 30 prostatic
glands.

24. Membranous Part: Runs downwards &
slightly forwards through the deep perineal
space & pierces the perineal membrane
about 2.5 cm below & behind the pubic
symphysis.
Narrowest& least dilatable part of urethra.
is surrounded by the sphincter urethrae or
external urethral sphincter.
Bulbourethral glands of Cowper are placed
one on each side of the membranous urethra.
Ducts of the gland open into spongy part of
urethra after piercing the perineal membrane

25. Spongy/Penile Part of Urethra :
• Fixed part in the bulb of the penis.
• Free part in the corpus spongiosum penis
• Terminates at the external urethral orifice
• Has uniform diameter of about 6 mm
two dilatations:
(a) In the bulb of penis -intrabulbar fossa
(b) In the glans penis- navicular fossa/terminal fossa
• ducts of the bulbourethral glands open into the
fixed part of the penile urethra about 2.5 cm below
the perineal membrane
• Urethral lacunae(of Morgagni) project from the
entire spongy part of the urethra except in the
terminal fossa which receives opening of Urethral
glands (Littre’s glands)
lacuna present in the roof of the navicular fossa is the
largest, and is known as the lacuna magna or sinus of
Guerin

26. Internal Sphincter(sphincter vesicae)
• surrounds the internal urethral orifice
• formed from the muscle of the bladder wall.
• is involuntary in nature & is supplied by
sympathetic fibres from (T11 to L2).
• It relaxes during urination but contracts during
ejaculation (to prevent the retrograde entry of
semen into the bladder).
External Sphincter (or Sphincter Urethrae)
• surrounds the membranous part of
the urethra
• formed by sphincter urethrae muscle.
• is voluntary in nature and is supplied by
pudendal nerve (S2, S3, S4).

27. FEMALE URETHRA:
• is only 4 cm long and 6 mm in diameter
• Begins at internal urethral orifice , traverses the urogenital diaphragm, and ends at
the external urethral orifice in the vestibule
• collections of mucous glands one on each side of the upper part of the urethra are
called the paraurethral glands of Skene. --are homologous to prostate
• female urethra is easily dilatable

28. Hypospadias:
Epispadias:
Catheterization of bladder:

29. THANK YOU