QS Study

The duodenum is the first component of the small intestine and is the continuation of the stomach. It is the first fraction of the small intestine, followed by the jejunum and ileum; it is also the widest and shortest part of the small intestine.

Parts of duodenum

Four Parts:

(1) 1st part or superior part 5 cm. It runs upward and backward on the right side of the first lumbar vertebra, thus it lies on the transpyloric plane.

(ii) 2nd part or descending part 7.5 cm. It runs vertically downward on the right side of second and third lumbar vertebrae, in front of the hilum of the right kidney.

(iii) 3rd part or horizontal part 10 cm. It passes in front of the vertebral column and follows the lower margin of the head of the pancreas.

(iv) 4th part or ascending pan 2.5 cm. It runs upward and to the left to the duodenojejunal flexure.

Fig: Parts of Duodenum

Blood supply on developmental background:

The duodenum develops partly from foregut and partly from the midgut. The opening of the bile duct into the 2nd part of duodenum represents the junction of the foregut and the midgut.

Arterial supply

(i) above the level of opening common bile duct, the duodenum is supplied by the superior pancreaticoduodenal artery of coeliac trunk.

(ii) Below the level of opening, it is supplied by the inferior pancreaticoduodenal artery.

1st part gets additional supply from:

a) Right gastric artery;

b) Supraduodenal artery, a branch of hepatic artery;

c) Retroduodenal br. of the gastroduodenal artery;

d) Branch of the right gastroepiploic artery.

Fig: Arterial supply and Venous drainage of Duodenum

Venous drainage – Ultimately these veins drain into the portal system, either directly or indirectly through the splenic or superior mesenteric vein.

The veins of the duodenum drain into:

(i) Splenic vein;

(ii) Superior mesenteric vein;

(iii) Portal vein.