Duodenum
Definition
It is the first and shortest part of the small intestine
25-30 cm
connecting the stomach to the jejunum
most chemical digestion takes place in this part of the intestine
It begins with the duodenal bulb and ends at the ligament of Treitz
Structure
Mucosa - circular folds - Brunner's glands
Muscularis mucosa
Serosa - only the anterior wall because it is almost entirely retroperitoneal
Parts
The duodenum is divided into four sections for the purposes of description.
The first three sections form a "C" shape.
First part
The first (superior) part begins as a continuation of the duodenal end of the pylorus.
5 cm
It is intraperitoneal.
Second part
The second is the descending part
The end of this part corresponds to L3
The pancreatic duct and common bile duct enter the descending duodenum through the major duodenal papilla.
Minor duodenal papilla is the entrance for the accessory pancreatic duct.
Third part
The third horizontal part passes transversely to the left, crossing the inferior vena cava, aorta and the vertebral column.
Fourth part
The fourth ascending part terminates at the duodenojejunal flexure where it joins the jejunum.
The duodenojejunal flexure is surrounded by a peritoneal fold containing muscle fibres: the ligament of Treitz.
Blood Supply
Arterial blood from two different sources.
Gastroduodenal artery and its branch the superior pancreatoduodenal artery.
Superior mesenteric artery, and its branch the inferior pancreatoduodenal artery
The venous drainage of the duodenum follows the arteries.
Into the portal system, either directly or indirectly through the splenic or superior mesenteric vein.
Lymphatic Drainage
Into the pancreatoduodenal lymph nodes
Into the pyloric lymph nodes
Into the superior mesenteric lymph nodes.
Into the celiac lymph nodes.
