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Where are the kidneys located?

The kidneys are retroperitoneal organs located on the posterior abdominal wall. The right kidney is slightly lower than the left kidney due to the downward displacement from the liver.


What are the important posterior relations of the kidneys?

Posteriorly, both kidneys are related to the diaphragm (separating the pleura), quadratus lumborum, psoas, transversus abdominis, the 12th rib and three nerves - subcostal (T12), iliohypogastric, and ilio-inguinal (L1)


What are the anterior relations of the kidneys?

The right and left kidney have different anterior relations.
The right kidney is related to the liver, the second part of the duodenum (which may be opened accidentally in performing a right nephrectomy) and the ascending colon.

In front of the left kidney lie the stomach, pancreas and its vessels, the spleen and the descending colon.


What is the renal hilum?

In the medial aspect of each kidney is a deep vertical slit called the hilum. This transmits from front to back, the renal vein, renal artery pelvis of the ureter and usually a subsidiary branch of the renal artery.

Lymphatics and nerves enter the hilum (these being sympathetic mainly vasomotor fibres).


How do anatomical variations in the renal pelvis make pyelolithotomy difficult?

Pyelolithotomy = removal of renal calculus. The renal. ureteric pelvis exhibits a large degree of anatomical variation. In some, it lies completely outside the substance of the kidney, or it may be almost completely buried in the hilum.

If a calculus is lodged in the pelvis, removal is much easier if the pelvis is located extrarenally compared to intrarenal.


How does the pelvis of the ureter divide once inside the kidney?

The pelvis of the ureter divides into two or three major calyces, each of which divides into a number of minor calyces. Each of those in turn is indented by a renal papilla where the collecting tubules of the kidney discharge urine into the ureter.


What are the layers of fat surrounding the kidney?

The kidneys lie in a fatty cushion called the perinephric fat. This is contained within the renal fascia. Above, the renal fascia blends with the fascia over the diaphragm leaving a separate compartment for the suprarenal gland.

Medially the fascia blends with the sheaths of the aorta and inferior vena cava. Laterally it is continuous with the transversalis fascia. It is only open inferiorly, tracking around the ureter into the pelvis.

The kidney is also surrounded by its own capsule.


Outline the blood supply to the kidneys

The renal artery derives directly from the abdominal aorta. The renal vein, drains directly into the IVC. The left renal vein passes in front of the aorta immediately below the origin of the SMA. The right renal artery passes behind the IVC.


What is the lymph drainage of the kidneys?

Lymphatics drain directly into para-aortic lymph nodes.


Where does blood from a ruptured kidney or pus in a perinephric abscess travel?

Blood from a ruptured kidney or pus from an abscess will first distend the renal fascia, then force their way within the fascial compartment downwards into the pelvis. The midline attachment of the renal fascia prevents extravasation to the opposite side.


What is "floating kidney"?

Floating kidney is also called hypermobility of the kidney. In this condition, the kidney can be moved up and down its fascial compartment but not side to side.


What are the components of the ureter?

The ureter is approximately 25cm long and comprises the pelvis of the ureter, and its abdominal, pelvic and intravesical portions.


Describe the course of the abdominal ureter

The abdominal ureter lies on the medial edge of psoas major (which separates it from the tips of the transverse processes of L2-L5). It crosses into the pelvis at the bifurcation of the common iliac artery in front of the sacroiliac joint.


What are the important relations of the abdominal ureters?

Anteriorly, the right ureter is covered at its origin by the second part of the duodenum and then lies lateral to the IVC and then behind the posterior peritoneum. It is crossed by the testicular, right colic and ileocolic vessels.

The left ureter is crossed by the testicular (or ovarian) and left colic vessels. It then passes above the pelvic brim, behind the sigmoid colon to cross the common iliac artery immediately above its bifurcation.


What is the course of the pelvic ureter?

The pelvic ureter runs on the lateral wall of the pelvis in front of the internal iliac artery to just in front of the ischial spine. It then turns forwards and medially to enter the bladder. In the male it lies above the seminal vesicle and is crossed superficially by the vas deferens.

In the female, the pelvic ureter runs downwards and forwards once it passes over the pelvic brim. It passes underneath the base of the broad ligament. As it does so it is crossed by the uterine arteries.


What is the blood supply to the ureter?

The ureter receives a segmented blood supply from all the available arteries along its course: the aorta, renal, testicular (or ovarian), internal iliac and inferior vesicle arteries.


How can the ureter be exposed surgically?

Throughout its abdominal and upper part of its pelvic course, the ureter adheres to the overlying peritoneum. As the parietal peritoneum is dissected upwards, the ureter comes into view sticking to its posterior aspect.


At what 3 sites is the ureter narrowed?

- at the junction of the pelvis of the ureter with its abdominal part
- at the pelvic brim
- at the ureteric orifice (narrowest of all)

A ureteric calculus is likely to lodge at one of these three levels


What are the anatomical relations of the male bladder?

The bladder sits in front of the pubic symphysis. Superiorly, it is covered by peritoneum. Behind is the rectum, termination of the vas deferens, and the seminal vesicles. Laterally, there is the levator ani and obturator internus muscles.

The neck of the bladder fuses with the prostate in the male, in the female it lies directly on the pelvic fascia surrounding the shorter urethra.

There is a layer of fatty connective tissue that sits between the bladder and the rectum in the male.


Describe the internal surface of the bladder

The bladder consists of smooth muscle lined with mucosa (uroepithelium). On each side, the ureters enter the bladder obliquely at the ureteric ostium. Urine leaves the bladder via the internal urethral meatus. There is a projection just above the meatus called the uvula.

The mucosal layer of the bladder is thrown into a trabecular arrangement which flattens out when the bladder is expanded. The mucosa becomes smooth in a triangle called the trigone, between the ureteric ostia and the internal meatus.


What is the blood supply to the bladder?

Blood is supplied from the superior and inferior vesical branches of the internal iliac artery. The vesical veins form a plexus which drains into the internal iliac vein.


What are the 3 parts of the male urethra?

1) prostatic
2) membranous
3) spongy


How does prostatic fluid enter the urethra?

The prostatic urethra is the first part of the urethra in the male. It passes through the substance of the prostate gland. Prostatic fluid contributes a portion of the seminal fluid and enters the urethra from its posterior wall. In fact there is a longitudinal ridge on the posterior wall of the prostatic urethra called the urethral crest. On each side of the crest is a shallow depression called the prostatic sinus into which the prostatic secretions empty and join the urethra.


What is the prostatic utricle?

The prostatic utricle must not be confused as the entry point for prostatic secretions into the urethra, they come from the prostatic sinus. The prostatic utricle sits at the middle of the urethral crest and is a blind passageway that passes upwards towards the middle lobe of the prostate. It is believed to be the male equivalent of the vagina and a remnant of the paramesonephric duct.


How does seminal fluid from the ejaculatory ducts enter the urethra?

The ejaculatory ducts form from the fusion of the ampulla of the vas deferens and the duct of the seminal vesicle. On either side of the orifice of the prostatic utricle are the openings of the ejaculatory ducts.


Describe the course of the membranous urethra?

The membranous urethra is the second part of the male urethral and emerges from the base of the prostate. In both males and females it must pass through the external sphincter (females only have an external sphincter) called sphincter urethrae. It is continuous with a sling of muscle that forms the pelvic diaphragm. The part that envelops the membranous urethra is called the levator prostatii. This is the most anterior and medial part of the pubococcageous muscle which in turn is part of the levator ani muscle complex.

Just below the pelvic diaphragm the membranous urethra passes through the perineal membrane.


In what structure is the spongy urethra located?

The spongy urethra traverses the corpus spongiosum of the penis. It first passes forwards to lie below the pubic symphysis, where it can be damaged by a fall astride a sharp object.


For what reason should catheters be introduced downwards into the beak of the urethra?

Immediately within the meatus, the urethra dilates into a terminal fossa with a roof that has a mucosal fold called the lacuna magna. This may catch the tip of a catheter which is why they should always be introduced downwards.


Describe the course of the female urethra

The female urethra is much shorter than the male and is surrounded by the external urethral sphincter muscle (sphincter urethrae). Unlike the males, the female urethra only has one sphincter. The female urethra is embedded in the wall of the vagina and opens into the vestibule of the vagina. Both the urethra and vagina pass through the pelvic diaphragm to enter the vestibule.

The external urethral meatus opens above the clitoris.


What is the mucosal lining of the urinary tract?

In both the male and female, the pelvis, ureter, bladder and urethra are lined by a transitional epithelium. In males, this extends to the entry of the ejaculatory ducts in the prostatic urethra. This is called uroepithelium.

The rest of the urethra has a columnar lining, except at its termination where the epithelium becomes squamous.