With the transverse colon and stomach reflected superiorly, identify the duodenum. This first portion of the small intestine encircles the head of the pancreas. The duodenum is about 25 cm long and consists of four parts (Figure 39.3). They are:
With the exception of its superior part, the duodenum is a retroperitoneal organ. The ascending part is continuous with the jejunum and becomes intraperitoneal at the duodenojejunal flexure. This flexure is located at the level of the L2 vertebra on the left side of the vertebral column. Observe also that the transverse mesocolon crosses the descending portion of the duodenum and attaches to the anterior surface of the pancreas.
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