Download Ureters, urinary bladder and urethra

URETERS, URINARY BLADDER AND
URETHRA
LEARNING OBJECTIVES
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At the end of the lecture the student should be able to
Identify ureter, urinary bladder and urethra
Identify the course and relations of ureter
Identify the parts and relations of urinary bladder
Identify the urethra
URINARY SYSTEM
 Consists of
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Kidney
Ureter
Urinary bladder
Urethra
URETER
 Thick-walled narrow cylindrical tube which is directly continuous near the lower end of
the kidney with the tapering extremity of the renal pelvis
 Convey the urine from the kidneys to the urinary bladder.
 25 to 30 cm. in length
 Has two parts
 Abdominal part
 Pelvic part
COURSE OF URETER
Completely retroperitoneal
 begins in the sinus of the kidney by the union of calyces.
 Renal pelvis (or pelvis of the ureter)– is dilated and emerges through the
lower part of the hilum.
 Runs downward along the medial border of the kidney, tapering to become
the ureter proper near the lower end of the kidney
 Ureter proper descends over the back wall of the abdomen, with a slight
medial inclination
 Enters the pelvic cavity by crossing the commencement of the external iliac vessels.
 Run posteroinferiorly on the lateral walls of the pelvis and then curve anteriormedially
to enter the bladder through the back
RELATIONS OF URETER
Right ureter
 lateral to the inferior vena cava.
 Its pelvic is covered by the second part of the duodenum and the renal
vessels.
 The ureter proper is covered with peritoneum, but four sets of vessels cross
in front of it, between it and the peritoneum, namely,
– Right colic artery
– Testicular or ovarian artery
– Ileocolic
– Superior mesenteric in the root of the mesentery
RELATIONS OF URETER
LEFT URETER
 lateral to the inferior mesenteric vein.
 Its pelvis is more exposed than that of the right
 After it escapes from behind the renal vessels, it is covered only by
the peritoneum.
 Ureter proper, as on the right side, is separated at intervals from the
peritoneum by vessels
– Upper left colic artery
– Testicular or ovarian artery
– Two or more lower left colic
CONSTRICTIONS OF URETER
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1.junction of ureter and renal pelvis
2.where ureters cross brim of pelvic inlet
3.during their passage through the wall of the urinary bladder.
These are the potential sites of obstruction by ureteric stones
URINARY BLADDER
 Musculo-membranous sac which acts as a reservoir for the urine
 Its size, position, and relations vary according to the amount of fluid it
contains.
URINARY BLADDER
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Empty bladder is in the lesser pelvis
Tetrahedral in shape
Presents a fundus, a vertex, a superior and an inferior surface.
Lie on the pubic bones, separated by retropubic space.
URINARY BLADDER
 When the bladder is moderately full it contains about 0.5 liter
 Assumes an oval form
 Exhibits
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postero-superior
antero-inferior
two lateral surfaces
Fundus
summit.
PARTS OF URINARY BLADDER
 Apex points towards the superior edge of pubic symphysis when bladder is
empty
 Fundus is opposite the apex, formed by convex posterior wall.
 Body is the major portion between apex and fundus
 Fundus and inferolateral surfaces meet inferiorly at the neck
RELATIONS OF BLADDER
 Inferolateral surface
– Pubic bones
– Levator ani
– Obturator internus
 Superior surface
– Peritoneum
 Fundus
 In male
– Posteriorly by rectovesical septum
– Laterally by seminal glands
 In female
– Vagina
MALE AND FEMALE BLADDER
LAYERS OF URINARY BLADDER
3 layers of unstriped muscular fibers
 External layer, composed of fibers having for the most part a longitudinal
arrangement
 Middle layer, in which the fibers are arranged, more or less, in a circular manner
 Internal layer, in which the fibers have a general longitudinal arrangement.
DETRUSOR MUSCLE
 The fibers of the detrusor muscle arise from the posterior surface of the body
of the pubis in both sexes (musculi pubovesicales)
 In male from the adjacent part of the prostate and its capsule
 At the sides of the bladder the fibers are arranged obliquely and intersect one
another.
Innervation of detrusor muscle
 When the bladder is stretched, this signals the
parasympathetic nervous system to contract the detrusor
muscle. This encourages the bladder to expel urine through
the urethra.
Ligaments of bladder
 Bladder is relatively free
 Held firmly anteriorly by its neck by
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lateral ligament of bladder.
Tendinous arch of the pelvic fascia
Puboprostatic ligament in males
Pubovesical ligament In females
 Posteriorly
– Directly upon anterior wall of vagina
Internal urethral sphincter
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Towards the neck of bladder the fibers form the internal urethral sphincter.
The muscle is made of smooth muscle
Under involuntary control.
It is kept tonically contracted by lumbar splanchnic nerves (L1-L2) of the
sympathetic nervous system.
 During micturition it is relaxed via the parasympathetic nervous system.
 This is the primary muscle for preventing the release of urine.
Trigone of bladder
 Trigone is a smooth triangular region of the internal urinary
bladder formed by
 Two ureteral orifices
 Internal urethral orifice.
Urethra
 Tube that connects the urinary bladder to the genitals for
removal out of the body.
 In males, Urethra travels through the penis, and carries
semen as well as urine.
 In females, the urethra is shorter and emerges above the
vaginal opening.
Male urethra
 Urethra is about 8 inches (20 cm) long and opens at the
end of the penis.
 In men divided into 4 parts, named after the location:
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Intramural (preprostatic) part
Prostatic urethra
Membranous urethra
Penile urethra
Female urethra
 Is a narrow membranous canal, about 4 cm. long, extending
from the internal to the external urethral orifice.
 Placed behind the symphysis pubis, embedded in the anterior wall of the vagina
 Its diameter when undilated is about 6 mm
 External orifice is situated directly about 2.5 cm in front of the vaginal opening.
Internal urethral sphincter
 located at the bladder's inferior end and the urethra's
proximal end at the junction of the urethra with the
urinary bladder.
 It is a continuation of the detrusor muscle
 made of smooth muscle, therefore it is under
involuntary or autonomic control.
 This is the primary muscle for prohibiting the release
of urine
External urethral sphincter
 located at the bladder's distal inferior end in females
 It is a secondary sphincter to control the flow of urine
through the urethra.
 Unlike the internal sphincter muscle, the external
sphincter is made of skeletal muscle, therefore it is
under voluntary control of the somatic nervous system.
References
 KLM clinical anatomy
 Gray’s textbook of anatomy
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