Blood supply of abdominal organs

Question 1

What are the main arteries that supply the abdomen?

Answer 1

• celiac trunk
• SMA
• IMA

Question 2

What does the celiac trunk supply?

Answer 2

foregut = abdominal esophagus –> superior to major duodenal papilla

Question 3

What does the SMA supply?

Answer 3

midgut = inferior to major duodenal papilla –> up to and including the proximal 2/3 transverse colon

Question 4

What does the IMA supply’?

Answer 4

hindgut = distal 1/3 transverse colon –> midway through anal canal

Question 5

What branches off the celiac trunk?

Answer 5

• left gastric A
• –esophageal branches
• splenic A
• –pancreatic branches
• –splenic branches
• –short gastric AA
• –left gastro-omental A
• common hepatic A
• –proper hepatic A
• ——left hepatic A
• ——right hepatic A
• ———-cystic A
• –gastroduodenal A
• —–supraduodenal A
• —–anterior and posterior superior pancreaticoduodenal A
• –right gastro-omental A

Question 6

What branches from the SMA?

Answer 6

• anterior and posterior inferior pancreaticoduodenal AA
• jejunal and ileal AA
  
  • arterial arcades
  • vasa recta
• middle colic A
• right colic A
• ileocolic A
  
  • colic, cecal, appendicular, ileal branches
• Marginal A

Question 7

What branches off the IMA?

Answer 7

• left colic A
• sigmoid AA
• superior rectal A

Question 8

Describe the arcades and vasa recta in the jejunum

Answer 8

arcades: large, fewer

vasa recta: long

Question 9

Describe the arcades and vasa recta in the ileum

Answer 9

arcades: small, many

vasa recta: short

Question 10

What is “Nutcracker Syndrome” aka renal vein entrapment?

Answer 10

• SMA passes anterior to left renal v and 3rd part of duodenum
• downward traction of SMA –> compression fo left renal v
• present with hematuria, proteinuria, left flank pain, N/V, left testicular pain in men

Question 11

Describe the hepatic portal V

• covered by what?
• formed from?
• carries?

Answer 11

• contained in hepatoduodenal L
• formed by splenic v and SMA merging
  - 1/3 cases IMV directly drains into HPV
  - 2/3 cases IMV drains into splenic V (60%) or SMV (40%)
• carries O2 poor blood and nutrients to liver

Question 12

What are the porto-caval anastamoses? What do they appear as in portal HTN?

Answer 12

Esophageal varices

• portal: esophageal v from left gastric v
• caval: esophageal v from azygos v

Hemorrhoids

• portal: superior rectal v (continues as IMV)
• caval: inferior rectal v and middle rectal v

Caput medusae

• portal: para-umbilical vv
• caval: epigastric vv

Other

• portal: visceral vv (colic, splenic)
• caval: retroperitoneal vv of posterior abdominal wall and diaphragm

Question 13

What is the blood supply of rectum above the pectinate line?

Answer 13

• derived from endoderm
• superior rectal a from IMA
• superior rectal v –> IMV –> portal system

Question 14

What is the blood supply of the rectum below the pectinate line?

Answer 14

• derived from ectoderm
• inferior rectal a from internal pudendal a
• inferior rectal v –>internal pudendal v –> internal iliac v –> common iliac v –> IVC

Question 15

Where does the aorta enter the aortic hiatus?

Answer 15

T12

Question 16

Where does the aorta end?

Answer 16

L4 dividing into right and left common iliac arteries

Question 17

Is the aorta intraperitoneal or retroperitoneal?

Answer 17

retroperitoneal

Question 18

What are the variations of the right hepatic artery to portal vein?

Answer 18

91% right hepatic artery is anterior to hepatic portal vein

9% right hepatic artery is posterior to hepatic portal vein

Question 19

What are the variations of arteries supplying the liver?

Answer 19

accessory or replaced right hepatic artery may originate from SMA
accessory or replaced left hepatic artery may originate from left gastric artery

Question 20

What does the hepatic portal vein sustain? What about the hepatic artery?

Answer 20

hepatic portal vein: liver parenchyma

hepatic artery: non-parenchymal structures (intrahepatic bile ducts)

Question 21

What is in the cystohepatic triangle of Calot?

Answer 21

• common hepatic duct
• cystic duct
• visceral surface of liver

Question 22

If the SMA is occluded, how can the pancreas get blood?

Answer 22

celiac artery –> common hepatic A –> gastroduodenal A –> superior pancreaticoduodenal A

Question 23

What are common variations in the SMA?

Answer 23

• common trunk for right and middle colic arteries
• common trunk for right and ileocolic arteries
• absent middle colic A replaced by a large branch from left colic
• absent right colic A

Question 24

What is the superior rectal artery from?

Answer 24

IMA

Question 25

What is the middle rectal artery from?

Answer 25

internal iliacs

Question 26

What is the inferior rectal artery from?

Answer 26

internal pudendal

Question 27

internal hemorrhoids

Answer 27

• visceral innervation
• not painful b/c above pectinate line
• prolapse of rectal mucosa that contains the normally dilated veins of the internal venous plexus
• bleeding is bright red due to the abundant ateriovenous anastamoses

Question 28

external hemorrhoids

Answer 28

• somatic innervation
• painful b/c below pectinate line
• thromboses or blood clots in veins of the external venous plexus
• covered by skin
• painful because they are located below the pectinate line and are innervated by somatic sensory fibers (inferior anal nerves)

Question 29

IVC

Answer 29

• begins anterior to L5
• 2.5 cm to the right of midline
• on the right side of the aorta
• passes through caval opening of diaphragm at T8
• longer than aorta