Duodenum, Pancreas and Portal Vein

Question 1

[3-minute video]: Portocaval Anastomoses

Answer 1

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Question 2

[5-minute video]: Blood Supply of the Pancreas

Answer 2

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Question 3

Click on Answer for transverse section images of the abdomen.

Answer 3

[Diagram 1] [Diagram 2] [Diagram 3] [Diagram 4] [Diagram 5]
[Image 1] [Image 2] [Image 3] [Image 4]

Question 4

State the location of the pancreas.

Answer 4

epigastric region, left hypochondriac region

Question 5

State five sites of portocaval (portosystemic) anastomosis and the vasculature involved.

Answer 5

1. Umbilicus: here the left branch of the portal vein communicates with the superficial veins of the anterior abdominal wall around the umbilicus, through paraumbilical veins of (Sappey). [In portal obstruction, the superficial veins around the umbilicus become distended and tortuous (varicosity). This whorl of prominent distended tortuous (snake-like) veins around the umbilicus is known as caput medusae—a sign of diagnostic value to the clinicians.]
2. Lower end of esophagus: Here the esophageal tributaries of left gastric vein (draining into the portal vein) anastomose with esophageal tributaries of accessory hemiazygos vein (systemic). In portal obstruction as in liver cirrhosis, these collateral channels become distended and tortuous, forming esophageal varices, which may rupture causing hematemesis (vomiting of blood) and may even bleed to death.
3. Anal canal: Here the superior rectal (hemorrhoidal) vein which ultimately drains into the portal vein anastomoses with middle and inferior rectal veins, the tributaries of internal iliac (systemic) vein. The distension and dilatation of these anastomotic channels result in the formation of hemorrhoids or piles which may be responsible for repeated bleeding per annum.
4. Extraperitoneal surfaces of retroperitoneal organs: Veins of retroperitoneal organs such as duodenum, ascending colon, and descending colon (portal) anastomose with the retroperitoneal veins of the posterior abdominal wall and renal capsule (systemic). The renal vein anastomosis with splenic and azygos veins.
5. Bare area of liver: Here the hepatic venules (portal) anastomose with phrenic and intercostal (systemic) veins.
6. [Diagram 1] [Diagram 2] [Diagram 3] [Diagram 4]

Question 6

State the anterior and posterior relations of the first part of duodenum.

Answer 6

Anteriorly: quadrate lobe of the liver and gallbladder
Posteriorly: portal vein, gastroduodenal artery, and the common bile duct
[Diagram] [Diagram 2] [Diagram 3] [Diagram 4]

Question 7

State the superior and inferior relations of the first part of the duodenum.

Answer 7

Superiorly: epiploic foramen being separated from it by the portal vein and bile duct
Inferiorly: Head and neck of pancreas
[Diagram] [Diagram 2] [Diagram 3] [Diagram 4]

Question 8

State the anterior, posterior, medial and lateral relations of the second part of the duodenum.

Answer 8

Anteriorly: Gallbladder and right lobe of the liver, transverse colon, transverse mesocolon (commencement), and coils of the small intestine
Posteriorly: Right kidney and right renal vessels, right edge of the inferior vena cava (IVC), and right psoas major muscle
Medially: Head of the pancreas
Laterally: From below upward, ascending colon, right colic flexure, and right lobe of the liver
[Diagram] [Diagram 2] [Diagram 3] [Diagram 4]

Question 9

State the relations of the:
(a) superior border of the head of the pancreas
(b) inferior border of the head of the pancreas
(c) right lateral border of the head of the pancreas

Answer 9

(a) superior border of the head of the pancreas:
⚚ first part of the duodenum
⚚ superior pancreaticoduodenal artery
(b) inferior border of the head of the pancreas:
⚚ third part of the duodenum
⚚ inferior pancreaticoduodenal artery
(c) right lateral border:
⚚ second part of duodenum
⚚ anterior and posterior pancreaticoduodenal arcades
[Diagram 1] [Diagram 2] [Diagram 3]

Further notes:
The superior pancreaticoduodenal artery is a branch of the gastroduodenal artery.
The inferior pancreaticoduodenal artery is a branch of the superior mesenteric artery.
[Image 1] [Image 2] [Image 3]

Question 10

State the relations of the:
(a) anterior surface of the pancreas [from above downward]
(b) posterior surface of the pancreas
(c) uncinate process [anterior and posterior]

Answer 10

(a) anterior surface [from above downward]:
⚚ gastroduodenal artery
⚚ transverse colon
⚚ root of the transverse mesocolon
⚚ jejunum

(b) posterior surface:
⚚ IVC
⚚ left renal vein
⚚ bile duct
⚚ right crus of diaphram

(c) uncinate process:
⚚ anteriorly to the superior mesenteric vessels
⚚ posteriorly to the abdominal aorta

Question 11

List the arteries that supply the duodenum.

Answer 11

(a) superior pancreaticoduodenal artery: branch of gastroduodenal artery
(b) inferior pancreaticoduodenal artery: branch of superior mesenteric artery
(c) supraduodenal artery of “Wilkie”: branch of gastroduodenal artery
(d) retroduodenal branches of the gastroduodenal artery
(e) branches from the right gastroepiploic artery
(f) artery from the first jejunal branch f the superior mesenteric artery: it supplies branches to the fourth part of the duodenum

Arteries (c), (d) and (e) exclusively supply the first part of the duodenum.

Further notes:
The upper half of the duodenum develops from the foregut and the lower half from the midgut. Therefore, the arterial supply of the upper half is derived from the coeliac trunk and that of the lower half from the superior mesenteric artery.