The significance of the morphology of the dorsal pancreatic artery in determining the presence of the accessory right hepatic artery passing behind the portal vein.

The dorsal pancreatic artery (DP) and an accessory right hepatic artery (AcRH) passing behind the portal vein were investigated in 98 Japanese specimens. The dorsal pancreatic artery was identified in 87 specimens (88.8%). This artery has been found to yield the following 6 branches: (1) an inferior pancreatic artery (left branch, 83.9%); (2) a right branch-1 that serves as the prepancreatic arcade in front of the pancreas (77.0%); (3) an uncinate branch that distributes to the uncinate process (60.9%); (4) a head branch that distributes from the dorsal side of the pancreas to the head of the pancreas (newly defined in the present study, 60.9%); (5) a right branch-4 that distributes superior to the dorsal part of the pancreatic neck (39.1%); and (6) a right branch-5 that communicates with the posterior pancreaticoduodenal arcade (21.8%). In some cases, the above six branches are formed separately, i.e., two (18.4%) or three (5.7%) dorsal pancreatic arteries are present. The parent artery of the DP was the superior mesenteric artery (SM; 55.0%), accounting for 45.0% of the entire celiac trunk. An accessory right hepatic artery was identified in 18 specimens (18.4%). In cases where the AcRH originated from the entire celiac trunk (5 specimens, 27.8%), it always formed a common trunk with the DP. On the other hand, when the AcRH derived from the SM (13 specimens, 72.2%), it formed a common trunk with the DP 6 of the specimens (33.3%), independent branching was observed in 6 specimens (33.3%). And a common trunk with the inferior pancreaticoduodenal artery was observed in one specimen (5.6%). The dorsal pancreatic artery was considered to supply not only the AcRH but also other pathways that form more complicated variations such as an accessory middle colic artery.