Lab Manual - Kidneys & Retroperitoneum

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. (explanation)
  2. Describe the basic internal gross anatomy of the kidney. (explanation)
  3. Define the blood supply and drainage of the kidneys and suprarenal glands. (explanation)
  4. Describe the general organization of the urinary and endocrine systems. (explanation)
  5. Know the pattern of diaphragmatic musculature and its fasciae, and its functional significance in respiration. (explanation)
  6. Know the three major passageways through the diaphragm and the structures traversing them. (explanation)
  7. Describe the position and vertebral level for all branches of the abdominal aorta and the inferior vena cava, and the reason for the difference in their patterns. (explanation)
  8. Identify the thoracic and lumbar splanchnic nerves and the collateral ganglia or regional subdivisions of the preaortic plexus to which each functionally relates. (explanation)
  9. Recall the concept of perivascular plexuses, their position, nomenclature, and nerve fiber components. (explanation)
  10. Describe the parasympathetic innervation of the GI tract. (explanation)
  11. Identify the cisterna chyli and describe the general pattern of lymphatic drainage to the thoracic duct. (explanation)
  12. Identify and demonstrate the abdominal attachments of the two major posterior abdominal wall muscles and know the action of these muscles upon the vertebral column. (explanation)
  13. Describe the nerves of the lumbar plexus in terms of their: spatial relationship to the posterior abdominal wall muscles; distribution to the abdominal wall, the genital region, and the lower limb; and categorization into purely cutaneous nerves and those which also innervate muscles. (explanation)
  14. Locate the lumbar sympathetic trunk and white and gray rami communicantes; explain the reason for the inferior limit of the white rami. (explanation)

Readings and Modules:

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, 331, 342A, 342B, 329, 342, 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.

Double ureter

4. Examine the left kidney and incise it in the frontal plane to examine its internal structure. (Play movie; View images: N 318, 332, 346A, 346B, 335, 341, 347, 346, 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.

Intravenous pyelogram

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. Clean and examine the diaphragm, its parts, apertures and the nerves, vessels and other structures passing through or behind it. (Play movie; View images: N 193, 194, 195, 253, 263, 266, 270, TG 5-07, 5-33, 5-38)

Review the thoracic and abdominal relations of the diaphragm. Consider its shape and attachments. Strip the peritoneum from its abdominal surface. Examine the fascia (transversalis) lining it. Trace to the posterior wall and identify the median, medial, and lateral arcuate ligaments. Note their relationship to the aorta, psoas major and minor, and quadratus lumborum muscles. How are these ligaments formed? Verify their bony attachments. Now strip the fascia from the diaphragm determining muscle fibers of sternal, costal and lumbar origins (medial and lateral arcuate ligaments). Clear and identify the central tendon. Elevate the kidney with its renal vessels and fat; now trace the crura of the diaphragm from the lumbar vertebrae to the central tendon, noting formation of the aortic hiatus (T12) and the esophageal hiatus (T10). Note the degree to which fibers of the two crura contribute to their formation. What is the lumbocostal trigone? Significance? Trace the phrenic nerves through the diaphragm and examine their distribution on the inferior surface. Are there other innervations? Examine the caval hiatus (T8). What are the differences in the formation and the structures transmitted by each diaphragmatic hiatus? What are the average vertebral levels of each?

Diaphragm
Left and right crura of the diaphragm

6. Examine the preaortic autonomic nerve plexuses of the abdomen and the branches of the abdominal aorta. (Play movie; View images: N 195, 209, 266, 266, 318, 319, 322, 323, 344, TG 5-34, 5-37, 5-38, 5-39, 8-16, 8-17)

Examine the pre-aortic autonomic plexuses of the abdomen, beginning with the celiac ganglia and celiac plexus. Define each and note arrangement around the celiac trunk. Trace the greater thoracic splanchnic nerve through the crus of the diaphragm to the celiac ganglion. Also locate the celiac branches of the posterior vagal trunk as they join the plexus. Significance? These structures are easier to see if the kidney is reflected medially with any fat remaining around it. Define the aorticorenal ganglion. Trace the lesser thoracic splanchnic nerve to its termination. Trace the celiac plexus to the superior mesenteric artery. Is there a superior mesenteric ganglion here? Now trace the intermesenteric plexus on the aorta to the inferior mesenteric artery. Is there an inferior mesenteric plexus here? Ganglia? Define and trace the superior hypogastric plexus. Complete the dissection of the thoracic splanchnic nerves by cutting through the diaphragm on the left side to each of the nerves and exposing their complete course (thoracic and abdominal). With the left crus of the diaphragm fragmented or removed, trace the thoracic sympathetic trunk into the abdomen noting change in location. How does it get into the abdomen? Trace the lumbar sympathetic trunk until it disappears behind the common iliac artery. Locate and identify the lumbar ganglia and the lumbar splanchnic nerves. How many splanchnic nerves are there? What part of the preaortic plexus do they join? At this time organize the autonomic distribution to the abdominal viscera. How is this distribution completed from the structures you have seen today?

Examine the abdominal aorta completely, locating place and level of entrance to abdomen, point and level of bifurcation, course, relations, branches, and vertebral levels of each. Now locate an example of the lumbar segmental arteries and the median sacral artery. How do these compare with the thoracic segmental vessels? Slit open the aorta and examine its posterior wall noting the manner in which the segmental vessels leave the aorta.

Trace the inferior vena cava from its formation from the union of the common iliac veins, noting course and relations to the aorta and viscera throughout the abdomen. Review tributaries throughout, including the right gonadal, renal, and right suprarenal veins. Now identify an example of the lumbar segmental veins. Do all terminate in the vena cava?

Note the lumbar lymph nodes located to the left of the abdominal aorta and around the inferior vena cava. What is the source of the afferent drainage of the lumbar lymph trunks and the intestinal lymph trunk? Examine the origin of the thoracic duct at the right of the aorta in the aortic hiatus. What is the cisterna chyli? Organize the parietal and visceral lymph drainage of the abdomen.

7. Fragment and remove the left psoas major (and minor if present) and examine the lumbar plexus of nerves and white and gray rami of the lumbar sympathetic trunk. (Play movie; View images: N 167, 263, 264, 265, 266, 491, 497, 498, 538, , TG 5-33,5-38, 5-40, 5-41,3-25, 5-33, 3-13, 5-38, 3-63, 5-34, 5-08, 5-37)

Clean the psoas major muscle and psoas minor, if you have one, as far as the inguinal ligament. Now fragment the left psoas muscle and remove, identifying the rami communicantes between the lumbar sympathetic trunk and the lumbar segmental nerves. How do you distinguish between the white and gray rami? How many white rami are there? Why?

With the left psoas muscle fragmented and removed, identify the lumbar segmental nerves and the resulting lumbar plexus of nerves. These nerves all have specific relationships to the psoas major and iliacus muscles, making them easier to identify. Identify and note course and relations of the subcostal, iliohypogastric, ilioinguinal, genitofemoral, lateral femoral cutaneous, femoral and obturator nerves. Trace only as far as the inguinal ligament. Clean the quadratus lumborum and iliacus muscles and note their relationships.

Psoas muscle

Identify the iliacus muscle in the iliac fossa and trace it along with the remains of psoas major to the inguinal ligament. Follow them into the thigh as the iliopsoas, noting its insertion and innervation. To what group of muscles does it belong? What are the actions of these muscles?

Identify the external iliac vessels as they pass beneath the inguinal ligament. Medial to the external iliac vein is the femoral ring. What ligaments surround it on three sides? Do you find a deep inguinal node within the femoral ring? Recall that the femoral ring is the abdominal opening of the femoral canal.

Updated: 11 January 2012