Human Anatomy - Lab 39 Step 7

Laboratory 39. Intestines and Pancreas
Step 7. The Duodenum

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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:

first or superior part
second or descending part
third or horizontal part
fourth or ascending part

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.

Links and References:
Grant's: 2.65,2.67,2.64B
Netter: 279
Rohen/Yokochi: 296,282,279