What are the four parts of the duodenum?

The duodenum is generally divided into four parts according to its location: duodenal bulb, descending part of duodenum, horizontal part of duodenum and ascending part of duodenum.

1. Duodenal

bulb is located at the junction of stomach and duodenum, connecting pylorus. Local mucosa is relatively smooth and prone to ulcer.

2. Duodenal

descending part is generally adjacent to pancreatic head, and the whole is descending. The mucosa in the lumen bulges inward, and there is duodenal papilla at the lower end.

3. Duodenal

horizontal part is generally located at the third lumbar vertebra, and the whole is transverse to the left, adjacent to superior mesenteric artery and superior mesenteric vein.

4. Duodenal

ascending part is generally connected with jejunum, forming duodenojejunal curve. The upper and lower ends are connected with diaphragm by striated muscle and smooth muscle respectively, and may be mixed with connective tissue.