Surgical anatomy of the innervation of pylorus in human and Suncus murinus, in relation to surgical technique for pylorus-preserving pancreaticoduodenectomy

Abstract

Aim: To clarify the innervation of the antro-pyloric region in humans from a clinico-anatomical perspective.

Methods: The stomach, duodenum and surrounding structures were dissected in 10 cadavers, and immersed in a 10mg/L solution of alizarin red S in ethanol to stain the peripheral nerves. The distribution details were studied to confirm innervations in the above areas using a binocular microscope. Similarly, innervations in 10 Suncus murinus were examined using the method of whole-mount immunohistochemistry.

Results: The innervation of the pyloric region in humans involved three routes: One arose from the anterior hepatic plexus via the route of the suprapyloric/supraduodenal branch of the right gastric artery; the second arose from the anterior and posterior gastric divisions, and the third originated from the posterior-lower region of the pyloric region, which passed via the infrapyloric artery or retroduodenal branches and was related to the gastroduodenal artery and right gastroepiploic artery. For Suncus murinus, results similar to those in humans were observed.

Conclusion: There are three routes of innervation of the pyloric region in humans, wherein the route of the right gastric artery is most important for preserving pyloric region innervation. Function will be preserved by more than 80% by preserving the artery in pylorus-preserving pancreaticoduodenectomy (PPPD). However, the route of the infrapyloric artery should not be disregarded. This route is related to several arteries (the right gastroepiploic and gastroduodenal arteries), and the preserving of these arteries is advantageous for preserving pyloric innervation in PPPD. Concurrently, the nerves of Latarjet also play an important role in maintaining innervation of the antro-pyloric region in PPPD. This is why pyloric function is not damaged in some patients when the right gastric artery is dissected or damaged in PPPD.

Figure 1

The innervation of the pyloric region from the view of the superior part of the pylorus, its schematic shows in Figure 3A. Hepatic divisions (a) join in the anterior hepatic plexus in the proper hepatic artery or the left/right hepatic artery (HA). The nerves ran along the right gastric artery (RGA) and its branches (PyA), and reached the pyloric region (Py) (c). The nerves (b) of Latarjet ran along the lesser curvature or the branches of the left gastric artery (LGA), intended for the antro-pyloric region. B is an enlargement of the box in A., the arrows show the nerves innervating the pyloric region from the right gastric artery. CHA, common hepatic artery; D, duodenum; E, esophagus; GB, gallbladder; GDA, gastroduodenal artery; L, liver; S, stomach.

Figure 2

Another specimen, its schematic shows in Figure 3B, showing a descending branch (b) originating from the hepatic division of the anterior vagal trunk passing through the hepatogastric ligament, obliquely downward, reaching the right gastric artery (RGA), innervating the pyloric region (Py). a is similar to a in Figure 1A, indicating the hepatic divisions. c, indicating the branches for the pyloric region from the nerves of Latarjet. CHA, common hepatic artery; D, duodenum; GB, gallbladder; L, liver; LGA, left gastric artery; S, stomach.

Figure 3

Diagram indicating the distribution in and around the cardia, the lesser curvature, the porta hepatica and the antro-pyloric region in 10 cadavers. Among them, A and B are diagrams of Figures 1A and 2, respectively. Five specimens, B, D, F, I and J, showed hepatic divisions joining directly to the right gastric artery, while, for the other specimens, after joining to the proper hepatic or hepatic artery, the nerves sent off some offshoots to the right gastric artery, and innervated the pyloric region. ALGA, accessory left gastric artery; CHA, common hepatic artery; CL, caudal liver; GB, gallbladder; L, liver; LGA, left gastric artery; Py, pylorus; PyA, pyloric artery; RGA, right gastric artery; SDA, supra-duodenal artery.

Figure 4

An example of innervation in the posterior part of the pylorus. The stomach was raised. The nerves originating from the right gastroepiploic artery (RGEA) or the gastroduodenal artery (GDA) running along the retroduodenal artery (RDA) (white arrow) or the infrapyloric artery (IPyA) (white arrowhead) reached the first duodenum posterior part and the pylorus of the posterior part.

Figure 5

Two cases showing innervation of the pyloric region (Py) in Suncus murinus by whole-mount immunostaining. High magnifications of the boxed areas in A and C are shown in B and D. White arrows show the nerves of Latarjet intended for the antro-pyloric region. Black arrows indicate the nerves arising from the right gastric artery (RGA), running along the pyloric artery (PyA), and reaching the pyloric region. An, pyloric antrum; CBD, common bile duct; Duo, duodenum; E, esophagus; L, liver; LGA, left gastric artery; P, pancreas; RGA/V, right gastric artery/vein; S, stomach. Scale bar = 2 mm in A and B.