Is connected to liver by hepatoduodenal ligament (part of lesser omentum)
Portal vein, bile duct, and IVC located posteriorly
Descending (second) part
Descends along the right of L1-L3
Contains major duodenal papilla on posteromedial wall = opening of hepatopancreatic ampulla
Horizontal (third) part
Crosses inferior vena cava (IVC), aorta, and L3 vertebra
Is crossed by superior mesenteric artery (SMA) and SMV and root of mesentery
Ascending (fourth) part
Ascends to L2 on the left side
Curves anteriorly at the duodenojejunal flexure
Flexure is supported by the ligament of Treitz
Vascular supply (Section 4-6: Abdomen-Visceral Vasculature)
Arteries
Gastroduodenal artery, branch of common hepatic → superior anterior and posterior pancreaticoduodenal arteries
SMA → anterior and posterior inferior pancreaticoduodenal arteries
Important anastomoses between celiac trunk and SMA via duodenal arteries
Veins
Follow the arteries
Drain directly or indirectly into the portal vein
Lymphatics
Follow the arteries
Drain into pancreaticoduodenal, pyloric, superior mesenteric, and celiac lymph nodes
Innervation (Section 4-7: Abdomen-Innervation)
Parasympathetic supply from the vagus via celiac and superior mesenteric plexuses
Sympathetic supply via celiac and superior mesenteric plexuses, traveling on pancreaticoduodenal arteriesJejunum and ileum
[Plate 273, Ileocecal Region]page 144
page 145Begins at duodenojejunal juncture and ends at ileocecal junction