=Pancreatico-gastric Folds.=--If we open the lesser peritoneal cavity by dividing the gastro-hepatic omentum and look into the background of the retro-omental space, we will see a fold of the secondary lining parietal peritoneum (derived from the mesogastrium), which can be traced from the cephalic border of the pancreas to the pyloric extremity of the stomach. This fold carries the hepatic artery to the lesser omentum behind the first portion of the duodenum, and is called the right or main pancreatico-gastric fold. A similar fold, further to the left, carries in a like manner the coronary artery of the stomach to the cardiac end of the lesser curvature. This fold forms the left or secondary pancreatico-gastric fold. Between the two folds the caudal margin of the Spigelian lobe projects into the lesser cavity.
The appearance of the two pancreatico-gastric folds in the adult human subject is well seen in Fig. 284.
[Illustration: FIG. 290.--Abdominal viscera of _Nasua rufa_, brown coaiti, with stomach turned up and great omentum divided. (From a fresh dissection.)]
Fig. 290 shows the abdominal cavity of _Nasua rufa_, with great omentum divided to bring into view the vessels passing from cœliac axis to liver and stomach and elevating the retrogastric parietal peritoneum to produce the pancreatico-gastric folds.
(The course of the hepatic artery from cœliac axis to liver in the dorsal view in the cat is seen in Fig. 223.)
[Illustration: FIG. 291.--Schematic transection through foramen of Winslow before adhesion of dorsal mesogastrium and mesoduodenum to parietal peritoneum.]
[Illustration: FIG. 292.--The same section after the adult conditions have been established by adhesion.]
Figs. 291 and 292 represent schematically cross-sections directly through the foramen of Winslow, showing the method by means of which the hepatic artery reaches the upper border of the duodenum and the effect of the adhesion of duodenum and mesoduodenum upon the disposition of the vessel.
The coronary artery, like the splenic, is at first situated between the layers of the dorsal mesogastrium (vertebro-splenic segment). Like the splenic the coronary artery becomes anchored to the abdominal background and placed secondarily behind the parietal peritoneum of the lesser sac by the adhesion of this mesogastric segment to the primitive parietal peritoneum. To reach the lesser curvature at the cardia and to run thence from left to right along the lesser curvature between the layers of the gastro-hepatic omentum, the vessel raises the investing parietal peritoneum (originally the right leaf of the dorsal mesogastrium) into a crescentic fold, extending between its origin from the cœliac axis at cephalic margin of pancreas and the beginning of the lesser curvature of the stomach. Hence this fold is called the left pancreatico-gastric fold. (Seen well in Fig. 284.)