Lab Manual - Urinary System

Assignments:

Learning Objectives:

Upon completion of this session, the student will be able to:

  1. Demonstrate the relationships of the kidneys and suprarenal glands to adipose and fascial coverings, lower ribs and other abdominal organs.
  2. Describe the basic internal gross anatomy of the kidney.
  3. Define the blood supply and drainage of the kidneys and suprarenal glands.
  4. Describe the general organization of the urinary and endocrine systems.
  5. Describe the routes and relationships of the ureters from the kidneys to the urinary bladder.
  6. Recognize the urinary bladder in either its expanded or contracted position, and determine the extent of its peritoneal covering.
  7. Identify the internal orifices of the bladder and differentiate the trigone region from the rest of the bladder lining.
  8. Describe the relationships of the bladder to other pelvic organs in both sexes.
  9. Differentiate between male and female urethrae.

Procedure:

1. Review the bony landmarks. (Play movie; View images: N 248, 273, 307, 329, 330, TG 5-03, 5-29, 5-30B, 5-30C, 5-31)

On the skeleton examine the lower thoracic and lumbar vertebrae. Note the orientation of the 11th and 12th ribs to the lumbar vertebrae. Identify the iliac crest, and note the vertebral level of an imaginary horizontal line drawn between the right and left iliac crests.

Examine the posterior body wall and the disposition of peritoneum, particularly the attachments of the mesenteries and the locations of the fusion fascias (areas in which organs and their mesenteries have become secondarily retroperitoneal). Carefully reflect the descending colon and its mesentery (with the left colic artery, inferior mesenteric vein and pelvic splanchnic nerves) toward the pelvis. Remove the remaining posterior body wall peritoneum.

2. Remove the pararenal fat from around the kidney, try to identify renal fascia. (Play movie; View images: N 263, 273, 329, 330, 349, 342A, 342B, 343, 354, TG 5-30, 5-31, 5-33, 5-42)

From superficial to deep, the kidney is surrounded by pararenal fat, which is superficial to a thin fascia called the renal fascia (clinical eponym: Gerota's fascia), deep to which is found the perirenal fat (or adipose capsule). The pararenal fat is most abundant posterior to the lower extremity of the kidney, but there may be some anterior as well. The anterior and posterior layers of the renal fascia fuse together above the suprarenal gland, forming a common investment for it and the kidney. Caudal to the kidney, the two layers remain separate, but become difficult to trace as they thin out. Medially the renal fascia loses its identity as it becomes continuous with the connective tissue around the inferior vena cava and aorta.

Carefully remove any pararenal fat anterior to the kidney, and try to identify the thin renal fascia without breaking through it. Once it is identified, remove all the rest of the fat superficial to it. Cut or break through the renal fascia near the lateral border of the kidney, and gently elevate the kidney and its perirenal fat out of the paravertebral gutter, leaving the posterior pararenal fat in the gutter. See if you can now find the posterior layer of the renal fascia, which may be adherent to either the para- or perirenal fat. Note that structures enter and leave the kidney along the medial border and can be elevated with it.

Examine the posterior body wall relations of the kidney and the shape of the paravertebral gutter. Return the kidney with its renal fascia and perirenal fat to its normal position. Review the anterior visceral relations of the kidneys.

3. Remove perirenal fat to expose the kidney and suprarenal gland and examine the parts and blood supply of both organs. (Play movie; View images: N 265, 318, 332, 333, 340, 341, 342, 400, 401, TG 5-29, 5-30, 5-31B, 5-31C, 5-34, 5-39)

Carefully remove the renal fascia and perirenal fat, exposing the kidney and suprarenal gland. Weak fibrous strands traverse the perirenal fat to connect the renal fascia with the renal (fibrous) capsule of the kidney. Note any capsular arteries and veins found in the perirenal fat. Note that a small amount of perirenal fat and renal fascia separates the suprarenal gland from the kidney.

Expose the anterior surface of the kidney. Trace the renal veins to the hilum of the kidney, noting differences on right and left. The left renal vein should receive particular attention in terms of length, relations (to aorta, superior mesenteric artery, left renal artery), and to the tributaries it receives. Reflect the left kidney toward the midline. While doing this, note that the left renal vein receives on its dorsal side a lumbar vein (usually the 2nd) as a tributary. Examine the renal arteries, noting their origin from the aorta and divisions as they near the kidney. Do you find supernumerary renal arteries? If present, they usually enter the inferior pole of the kidney. What is their developmental significance? Note nerve plexuses along the renal arteries.

CT of renal vessels

Locate the gonadal arteries (ovarian or testicular). Trace to the pelvic brim, noting level of origin, variations, course, relations, branches. Note the course of the gonadal veins.

Examine the ureter and trace it to the pelvic brim. Note its relationship to the gonadal vessels. On the left note the relationship to the left colic vessels, and on the right to the root of the mesentery. Try to find small arteries to the abdominal ureter from the aorta, renal, gonadal, and common iliac arteries.

4. Examine the left kidney and incise it in the frontal plane to examine its internal structure. (Play movie; View images: N 308, 332, 334A, 334B, 335, 341, 347, 348, TG 5-30A, 5-30B, 5-31, 5-32A, 5-32B, 5-39, 8-16)

Mobilize both kidneys and remove any fat on the surface. Examine its renal (fibrous) capsule and hilum. At the hilum note the relationships between the renal artery, renal vein and renal pelvis (pelvis of ureter). Incise the left kidney along a frontal plane and define the sinus of the kidney. Trace the renal artery and its anterior and posterior divisions (leading to segmental branches). Observe the cortex and its renal columns; the medulla and its renal pyramids and renal papillae. Try to find an interlobar artery (adjacent to a renal pyramid). Trace the ureter to the renal pelvis and then to a major calyx and minor calyx. How many minor calyces do you find? Note their relationship to the renal papillae.

Examine the differences between right and left suprarenal glands in terms of shape and relationship to kidney. What is the relationship of the right gland to the inferior vena cava? Examine the abundant blood supply to the gland. Carefully try to verify the presence of numerous, very delicate superior, middle, and inferior suprarenal arteries that pass to the periphery of the gland from 3 sources: inferior phrenic artery, aorta, and renal artery. Find the single, relatively large suprarenal vein that passes out of the hilum of the gland. Note that on the right side, this vein and the inferior phrenic vein drain into the inferior vena cava. On the left side, both drain into the left renal vein. What other vein drains into the left renal vein?

CT of the suprarenal glands

Carefully elevate a suprarenal gland from the adipose capsule and note a branch of the greater thoracic splanchnic nerve entering it. This provides preganglionic sympathetic innervation to the medulla of the gland. Where are the postganglionic neurons located? Identifty the cortex and medulla.

5. Examine the external genitalia of both sexes. (Play movie; View images: N 351, 377, 382, 387A, 387B, 390, 398, TG 6-02, 6-25A, 6-25B, 6-31)

Before proceeding with the midsagittal section of the pelvis below, identify the external genitalia of both sexes: Female external genitalia: vulva, mons pubis, labia majora and their anterior and posterior commissures; labia minora and associated frenulum; clitoris and its glans, and prepuce; vestibule and its vaginal orifice and external urethral meatus. Male external genitalia: penis, prepuce, frenulum, glans, corona, external urethral meatus, body and dorsum of the penis, scrotum, and scrotal raphe. Now continue with dissection procedures on either male or female, but be sure to review all structures on a cadaver of the opposite sex as well.

6. Make a midsagittal section of the pelvis of the cadaver, removing the right pelvis and lower limb at the 4th lumbar vertebra. (Play movie; View images: N 360, 361, TG 6-08A, 6-08B)

Make a careful midsagittal section of the pelvis. Cut all soft tissues, including all genital organs, with a sharp scalpel as close to the actual midline as possible, and use the saw to cut the pubic symphysis, sacrum and last two lumbar vertebrae. On the right side cut half way through the disk between the third and fourth lumbar vertebrae to meet the sagittally-sectioned pelvis. This will keep the posterior abdominal wall intact and continuous with the left half of the pelvis and one lower limb. Thoroughly wash all fecal material out of the rectum on both sides.

7. Remove the peritoneal covering of the bladder and examine. (Play movie; View images: N 360, 361, 362, 366, 402, 403, 406, 407, 408, 410, TG 6-07A, 6-07B, 6-08A, 6-08B, 6-10A, 6-10B, 6-17A, 6-17B, 6-19A, 6-19B, 6-33, 6-34)

Urinary bladder: Observe peritoneal coverings of the urinary bladder. Note the different reflection in male and female. Remove the peritoneum and identify the urachus (median umbilical ligament). Examine the musculature of the bladder wall and identify the ureteric orifices, the interureteric crest, the urethral orifice, and the trigone. In the male look for a uvula. Blood supply, innervation and lymphatic drainage of the bladder will be exposed in a later dissection.

Urinary bladder

Explore the female urethra and note length, sphincter muscle, relation to vagina. Note specifically the relation of the orifice to the anterior vaginal wall. Significance? Where the neck of the bladder meets the pelvic diaphragm and posterior side of the pubis, identify the pubovesical ligament. Examine the sphincter urethrae muscle, and the membranous portion of the urethra.

Consider the blood supply and venous drainage of the ovary, uterine tube, uterus, vagina.

8. Examine the male genital tract, remove endopelvic fascia surrounding seminal vesicles. (Play movie; View images: N 352, 359, 361A, 361B, 362, 363, 365, 384A, 384B, TG 5-07, 6-07, 6-08, 6-09, 6-10, 6-14, 6-15, 6-31)

Ductus deferens (vas deferens): Trace, and note structure, course and relations to testis. Review course through spermatic cord and inguinal canal. After it passes through the deep inguinal ring, trace under the peritoneum and note relations to inferior epigastric artery, external iliac vessels, medial umbilical ligament, the ureter and the seminal vesicle. Define the ampulla of the ductus deferens. Are any of these structures covered by peritoneum? What is the rectovesical pouch?

Seminal vesicle: Remove the endopelvic fascia from the posterior surface of the bladder and expose the seminal vesicle, noting its relation to the ductus deferens, the ampulla, and bladder. Note the ureter and its point of entrance to the bladder; trace it through the pelvis and note its relation to the peritoneum and location as it enters the pelvis. Examine the junction of the ampulla and the duct of the seminal vesicle as they unite to form the ejaculatory duct. Open the seminal vesicle and examine its structure.

Vasogram

Prostate: Examine the prostate gland and attachments to the pubis via the puboprostatic ligament. Note relation of prostate to bladder, urogenital hiatus and rectum (ampulla). Trace the course of the ejaculatory duct. In the prostatic urethra, examine the urethral crest, prostatic sinus, colliculus seminalis and note specifically the openings of the ejaculatory ducts.

Examine the sphincter urethrae muscle around the lower portion of the prostate and proximal part of the urethra. The muscle may be difficult to distinguish.

Review the urethra and determine prostatic, membranous, and penile (spongy) parts.

Male urethrogram
Obstructed ureter

9. Clean and identify the branches of the internal iliac artery, removing the corresponding veins. (Play movie; View images: N 253, 255, 264, 267, 363, 364, 398, 400, 401, 402, 403A, 403B, 404A, 404B, 405, 487, 502, 503, TG 3-27, 3-28, 3-55, 5-05, 5-07A, 5-07B, 5-08D, 5-09D, 6-07, 6-09A, 6-09B, 6-17A, 6-17B, 6-22, 6-29A, 6-29B)

Pull the viscera (rectum, uterus, vagina, bladder) toward the midline to expose the structures lying adjacent to the lateral pelvic wall. Review the course of the ureter in both male and female.

Locate the common iliac artery and vein, note course and relations and point of bifurcation. Trace the external iliac artery and vein along the brim of the pelvis and note their relationship as far as the inguinal ligament. Review the inferior epigastric artery and its relationships.

Identify the internal iliac vein. Trace its major tributaries, then remove the veins to expose the internal iliac artery. The internal iliac artery commonly divides into anterior and posterior divisions. The posterior division gives rise to the iliolumbar artery, the lateral sacral artery (sending branches into the anterior sacral foramina), and the superior gluteal artery (passes out of the pelvis over the superior border of the piriformis muscle). Locate the anterior division and note how it terminates by dividing into the inferior gluteal and the internal pudendal arteries. These exit the pelvis below the lower border of the piriformis muscle (other relations?). Return to the proximal part of the anterior division and trace the branches to pelvic viscera: the umbilical artery and its superior vesical branches (note its continuation as the medial umbilical ligament or obliterated umbilical artery); identify the uterine artery, the vaginal artery, the middle rectal artery, and the obturator artery. Do you have an "aberrant obturator artery", which arises from the inferior epigastric artery and accompanies the obturator nerve? Organize the blood supply to the base of the bladder, prostate, seminal vesicles.

Arteriogram of pelvic vessels
Arteriogram of occluded vessels

10. Identify the nerves of the pelvis. Identify the muscles of the pelvic wall and floor. (Play movie; View images: N 367A, 367B, 368, 369, 370, 402, 403, 409, 410, 412, 415, 416, 417, 497, 499A, 499B, 502, 503, TG 3-25A, 3-25B, 3-26, 3-28, 6-04, 6-15A, 6-15B, 6-18A, 6-18B, 6-17, 6-18A, 6-18B, 6-19A, 6-19B, 6-21A, 6-21B, 6-22A, 6-22D, 6-23A, 6-23B, 3-27)

Locate the first four sacral nerves as they emerge from the anterior (pelvic) sacral foramina. Locate the lumbosacral trunk; note its course, the relation of the superior gluteal artery to it and the first sacral nerve. Examine the formation of the sacral plexus.

Pick up the superior hypogastric plexus on the bifurcation of the aorta and trace it into the pelvis. Note its division into hypogastric nerves and their continuity into the inferior hypogastric (pelvic) plexus. Locate the sympathetic trunk entering the pelvis along the medial border of the pelvic sacral foramina. Note ganglia (number? ), gray rami communicantes, sacral splanchnics. Now return to the sacral nerves and identify the pelvic splanchnic nerves. How many are there? Trace them to the inferior hypogastric plexus and search for branches passing up into the sigmoid mesocolon and to the descending and sigmoid colon. Consider subsequent distribution to rectum, vagina, uterus, bladder, prostate. Organize your knowledge of the autonomic (sympathetic and parasympathetic) supply to the pelvic viscera.

Reflect or mobilize the pelvic viscera medially on one side only. Locate the obturator internus muscle and define its fascia. Locate its thickening, the arcus tendineus levator ani. Determine the parts of the pelvic diaphragm and trace each. Distinguish between the levator ani and the coccygeus muscles. What is the puborectalis muscle; significance? Define the urogenital hiatus. What does it transmit?

Examine the piriformis muscle and note its attachment to the sacrum, as well as its relation to the sacral nerves, to the sacral plexus and to the superior and inferior gluteal arteries.

Lymphangiogram of iliac lymph nodes and vessels