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The blood supply to all the organs in the abdomen that we've seen so far, the GI tract, the liver, pancreas and spleen, comes from three midline branches of the abdominal aorta. These are the celiac, the superior mesenteric and the inferior mesenteric arteries. We'll look at these, then we'll look at the special venous drainage of these organs.

We'll start with the celiac artery, which is more often called the celiac trunk or axis because it's so short. It supplies the structures that are derived from the foregut: the stomach, proximal duodenum, spleen, liver, and most of the pancreas.

To see the celiac trunk and its branches we'll start here in the upper abdomen, in a specimen in which the arteries have been injected with latex. We've removed the lower part of the rib cage, and we've removed the left lobe of the liver, which was here.

The celiac trunk arises back here. To see it we'll take the stomach and the lesser omentum out of the picture. We've also removed all the fatty connective tissue from this uppermost part of the posterior abdominal wall. Here's the opening in the diaphragm for the esophagus. Here below it is the opening for the aorta. Here's the aorta itself, just visible above the pancreas.

This short vessel coming straight forwards is the celiac trunk. It arises right at the top of the aortic opening, between the crura of the diaphragm. The celiac trunk gives off branches to the diaphragm, then divides into three main branches, the small left gastric artery which goes straight up, and the large common hepatic, and splenic arteries, which go to the right and left.

We'll look at the splenic artery first. The splenic artery follows a tortuous course towards the spleen along the upper border of the pancreas. Here's the pancreas, here's the spleen. The splenic artery ends by dividing into several large branches as it reaches the hilum of the spleen.

Now we'll follow the follow the other main branch of the celiac axis, the common hepatic artery. The common hepatic artery passes to the right, and divides into the hepatic artery, and the gastro-duodenal artery. The hepatic artery runs upwards and to the right, to supply the liver.

It runs close to the common bile duct, which is here, and the portal vein, which is beneath it here. To follow the hepatic artery, we'll look at the liver from behind. Here's the hepatic artery, dividing into right and left branches as it approaches the porta hepatis. This is the portal vein, which we'll come to shortly.

We'll return to the division of the common hepatic, into the hepatic and gastro-duodenal arteries. From near this division two branches to the stomach arise, the right gastric, which usually arises from the hepatic, and the right gastro-epiploic, which arises from the gastro-duodenal.

After giving off the right gastro-epiploic, the gastro-duodenal artery continues as the pancreatico-duodenal artery. It runs downward behind the duodenum, supplying it and the head of the pancreas. Here the divided duodenum has been retracted to the right. Normally, it's here.

Now we'll look at the blood supply to the stomach, which we'll put back into the picture. The stomach gets most of its blood supply from two vascular arcades, an outer one, that runs in the greater omentum or gastro-hepatic ligament, close to the greater curve, and an inner one that runs in the lesser omentum near the lesser curve.

The inner arcade is supplied at its two ends by the right gastric, and left gastric arteries. The outer arcade is supplied by the right gastro-epiploc, and the left gastro-epiploic which is a branch of the splenic. Often the right and left vessels join to form a continuous loop.