Before we leave the duodenum, we need to look at two special aspects of its peritoneal attachments: proximally, the distal part of the lesser omentum, and distally the suspensory ligament.
We'll go back to this earlier stage of the dissection to see these. Here's the part of the lesser omentum that we've seen already. The lesser omentum continues along the upper surface of the first part of the duodenum, and comes to an end here.
This is the free border of the lesser omentum, passing from the duodenum to the underside of the liver. Beneath the free border of the lesser omentum lies this hidden opening, the epiploic foramen, which is the only natural entry way to the omental bursa or lesser sac.
Going to the distal end of the duodenum, this is the suspensory ligament, also known as the ligament of Trietz. It's a fold of peritoneum, reinforced with fibrous tissue, that holds up the duodeno-jejunal flexure.