Retroperitoneum and Posterior Abdominal Wall

Question 1

Retroperitoneal Space and Organs

Answer 1

•	Retroperitoneal space – between posterior parietal peritoneum and transversalis fascia
o	S – suprarenal glands
o	A – aorta/IVC
o	D – duodenum (2nd, 3rd, part of 4th)
o	P – pancreas (NOT the tail)
o	U – ureters
o	C – colon (ascending and descending)
o	K – kidneys
o	E – esophagus
o	R – rectum

Question 2

Kidney Layers

Answer 2

o Coverings (from outside in)
 Paranephric adipose tissue
 Renal fascia (Gerota’s fascia) – separates fat layers and is continuous with transversalis fascia
 Perinephric adipose tissue – space between renal fascia and kidney

Question 3

Kidney Components

Answer 3

 Renal fascia
 Capsule
 Cortex – has extension into renal medulla (renal columns) where blood vessels are
 Medulla
• Renal papilla
• Pyramids – location of collection tubules, loops of Henle, etc.
 Renal Sinus
 Minor calyces  Major calyx  renal pelvis  ureter
 Ureters

Question 4

Kidney Location

Answer 4

o Location
 Right kidney (rib 12: L1-L4) lies mostly under the liver and is slightly lower than left kidney
 Left kidney (rib 11: T12-L3) lies mostly under the stomach
o Surface Anatomy – on posterior wall of abdominal cavity under rib cage anterior to rib 11/12

Question 5

Kidney Relations to other structures

Answer 5

 BOTH KIDNEYS ARE:
• Lateral to IVC and aorta
• Inferior and in close contact with diaphragm
• In contact with adrenal glands on their rostral (superior) tips
 Anterior to Right Kidney is liver, duodenum, right colon
 Anterior to Left Kidney is spleen, stomach, pancreas, left colon, small gut

Question 6

Kidney Plumbing

Answer 6

– receive about 25% of cardiac output; renal vein, artery, pelvis (anterior  post.)
 Arteries – renal arteries arise at level of L1-L2; right renal artery is longer than left and passes posterior to IVC
• Each renal artery divides into 5 renal segmental arteries
 Veins – renal veins are anterior to renal arteries; left renal vein is anterior to aorta with superior mesenteric running over the left renal vein (“nutcracker angle”)
• Left gonadal & left suprarenal veins drain into the left renal vein
• Right gonadal & right suprarenal veins drains directly into IVC

Question 7

Ureter Structure, location, pain

Answer 7

muscular ducts with narrow lumens
o Location – anterior to the tips of transverse processes of lumbar vertebrae
o Narrowings (likely place where kidney stones could get stuck)
 Ureteropelvic junction (UPJ) - junction of renal pelvis and ureter
 Pelvic brim
 Wall of urinary bladder
o “Rebound pain” when comparing appendix and stone stuck in right ureter; kidney will not experience rebound pain because it is retroperitoneal and lacking parietal peritoneum resulting in less pain experienced when pushing on Low R. Quad.
o Patients suffering from pathology (displacement, blockage, etc.) will succumb to renal failure first if renal function is compromised – will develop uremia

Question 8

Ureter Blood Supply & Lymphatics

Answer 8

o Blood Supply
 Renal, gonadal, common iliac, internal iliac arteries
 In abdomen blood supply arrives medially; in pelvis blood arrives laterally
o Lymphatics
 Superior part – follows renal
 Middle part – common iliac nodes  lumbar nodes  cysterna chili
 Inferior part – common iliac, external iliac, OR internal iliac nodes

Question 9

Suprarenal/Adrenal Glands Shape, Blood Supply, Structure

Answer 9

o Right adrenal gland – triangular shaped
o Left adrenal gland – semilunar shaped
o Blood Supply
 Superior suprarenal arteries (branch of inferior phrenic artery)
 Middle suprarenal arteries (branch of abdominal aorta, near superior mesenteric artery)
 Inferior suprarenal arteries (branch of renal arteries)
 Venous drainage via one large suprarenal vein for each gland; drains into left renal vein on left side and directly into IVC on right side
o Cortex – secretes steroid-type hormones; controlled by hormones
o Medulla – secretes catecholamine-type hormones; controlled by PREsynaptic sympathetic fibers; ONLY FOR MEDULLA (ventral rami  paravertebral ganglion  abdominopelvic Splanchnic nerve  prevertebral (preaortic) ganglia  medulla (synapse))

Question 10

Anterior Abdominal Wall Blood Supply and Lymphatics

Answer 10

-Superiorly – internal thoracic artery divides:
• Musculophrenic – supplies lateral wall
• Superior epigastgric artery – enters rectus sheath and anastomoses with inferior epigastric artery
-Inferiorly – 2 arteries arise from external iliac
• Deep circumflex iliac artery – provides blood to infero-lateral part of wall
• Inferior epigastric artery – enters rectus sheath at arcuate line to anastomose with superior epigastric artery
o Medial to deep inguinal ring – explains difference in hernias
-Laterally – lower intercostals arteries
o Veins – follow same path as arteries
-Lymphatics
 Above umbilicus – drains to axillary nodes of corresponding side
 Inferior to umbilicus – drain to superficial inguinal lymph nodes

Question 11

Abdominal Aorta - 3 unpaired visceral branches, 3 paired visceral branches, 3 paired parietal branches, 1 other

Answer 11

– runs behind diaphragm at T12 and ends left of midline at L4
3 unpaired visceral branches – generally distributed to foregut, midgut, hindgut
	Celiac (L1)
	Superior mesenteric (L1)
	Inferior mesenteric (L3)
3 paired visceral branches
	Suprarenal
	Renal
	Gonadal 
3 paired parietal branches
	Inferior phrenic
	Lumbar
	Common iliac

Question 12

Inferior vena Cava - 2 unpaired visceral branches, 2 paired visceral bracnhes, 3 paired parietal branches

Answer 12

– pierces diaphragm at level of T8 and extends to level L5 where 2 common iliac veins come together to form IVC
2 unpaired visceral branches
	Right suprarenal
	Right gonadal
2 paired visceral branches
	Hepatics
	Renal
3 paired parietal branches
	Inferior phrenic
	Lumbar
	Common iliac

Question 13

Autonomics To Visceral Organs

Answer 13

o Autonomics to Visceral Organs
 Sympathetic innervation – from thoraco-lumbar splanchnic nerves
 Parasympathetic innervations – vagus nerve up to left colic flexure; pelvic Splanchnic nerves from left colic flexure to rectum
o Splanchnic Nerves – pass from sympathetic trunk/ganglia to prevertebral plexus/ganglia anterior to aorta (all are pre-ganglionic)
 Sympathetic Thoracic Splanchnic Nerves
• Greater – T5-T9; goes to celiac plexus
• Lesser – T9-T10; goes to aorticorenal ganglion
• Least – T12; goes to renal plexus
 Parasympathetic Pelvic Splanchnic Nerve from S2-S4 (pelvic plexus)

Question 14

Clinical Correlation: Pain Sequence & Appendicitis

Answer 14

 1st level of pain – general ill defined pain in one of abdominal regions
 2nd level of pain – involved organ becomes infected and adheres to parietal peritoneum causing localized pain to a specific region of anterior abdominal wall
• Physician can elicit pain by palpating area
• Upon releasing the affected area, the pain becomes sharp – rebound tenderness
 Appendicitis
• General ill feeling around umbilicus (T10)
• Inflammation of appendix reaches parietal peritoneum and illicit localized pain; can occur even if appendix does not rupture (ruptures only 10-15% of time)
o Makes not of patient “guarding” or not
• In time, pain begins to be felt around tip of shoulder  example of referred pain due to peritoneal infection moving to undersurface of diaphragm which is innervated by C3/4/5

Question 15

Diaphragm Ligaments

Answer 15

right crus lower than left crus
o Median arcuate ligament – goes around aorta
o Medial arcuate ligament – goes around psoas major
o Lateral arcuate ligament – goes around quadratus lumborum

Question 16

psoas major

Answer 16

genitofemoral nerve pierces through it
 Location – lumbar vertebral bodies and transverse processes to lesser trochanter of femur
 Innervations – ventral rami of L1-L4
 Action – flexes thigh; laterally bends vertebral column; allows us to walk and do sit ups

Question 17

psoas minor

Answer 17

 Location – bodies of T12 & L1 vertebrae to lesser trochanter of femur
 Innervations – ventral rami of L1-L2
 Action – flexes and laterally bends vertebral column

Question 18

iliacus

Answer 18

– inserts in company with psoas major via iliopsoas tendon
 Location – iliac fossa/crest and sacrum to lesser trochanter of femur
 Innervations – femoral nerve (L2, L3)
 Actions – flexes thigh

Question 19

quadratus lumborum

Answer 19

 Location – posterior part of iliac crest and iliolumbar ligament to transverse process of lumbar vertebrae L1-L4 and 12th rib
 Innervation – subcostal nerve (T12) and ventral rami of L1-L4
 Action – laterally bends the trunk; fixes the 12th rib

Question 20

transversus abdominis

Answer 20

 Location – lower 6 ribs, thoraco-lumbar fascia, iliac crest, inguinal ligament to linea alba, pubic crest and pubis
 Innervations – intercostals nerves 7-11, subcostal, iliohypogastric and ilioinguinal nerves
 Action – compresses the abdomen

Question 21

Clinical Correlation: Iliopsoas Test

Answer 21

performed when intra-abdominal inflammation is suspected or to test the muscle itself
 Patient lies on unaffected side and flexes the affected leg  pain = positive psoas sign and potentially inflamed appendix
 Covering of psoas muscle can thicken and becomes a stocking-shaped tube; pus from psoas abscess may travel down to inguinal region presenting as lump in groin

Question 22

Major Holes in Diaphragm

Answer 22

o	T8 – Inferior vena cava & right phrenic nerve
o	T10 (esophageal hiatus) – esophagus, vagal trunks, left gastric branches
o	T12 (aortic hiatus) – aorta, thoracic duct, azygous vein