Gastric plexuses

Gastric plexuses refer to a meshwork of autonomic neurons and ganglia situated around the gastric arteries. They are considered to be periarterial extensions of the celiac plexus, which spread along the branches of celiac trunk to innervate various parts of the stomach.

Gastric plexuses can be divided into superior and inferior:

• The superior gastric plexus accompanies the left gastric artery along the lesser curvature of stomach.

• The inferior gastric plexus is formed by periarterial plexuses of right and left gastroepiploic arteries. The right gastroepiploic arterial plexus derives its neurons from the hepatic and gastroduodenal arterial plexuses. While the left gastroepiploic arterial plexus derives its neurons from the splenic plexus.

The gastric plexuses contain both efferent sympathetic and parasympathetic neurons:

The sympathetic innervation of the stomach comprises of pre-ganglionic fibers, which arise from the lateral horns of lower thoracic spinal segments and are distributed to the celiac and gastric plexuses via greater and lesser splanchnic nerves.

The parasympathetic innervation of the stomach comprises of pre-ganglionic neurons, which originate from the dorsal motor nucleus of vagus. They reach the celiac and gastric plexuses via branches of the anterior and posterior vagal trunks. The postganglionic parasympathetic neurons are very small and situated within the walls of the viscera, such as, the Myenteric and Meissner’s plexuses within the gut wall.

The branches of anterior vagal trunk, which supply parasympathetic neurons to the celiac and gastric plexuses include the anterior gastric branches, the anterior nerve of lesser curvature, hepatic and pyloric branches. Whereas, the branches of posterior vagal trunk, which supply parasympathetic neurons to the celiac and gastric plexuses include the criminal nerve of Grassi, celiac branches, posterior gastric branches and the posterior nerve of lesser curvature.

The sympathetic innervation causes vasoconstriction, inhibits gastric motility and constricts the pylorus. Whereas, the parasympathetic innervation leads to vasodilatation, increase gastric motility and opens up the sphincters.

The autonomic neurons within gastric plexuses are also accompanied by visceral afferent neurons. These are sensory in nature and transmit pain sensation from the stomach to the central nervous system. The pain is poorly localized and is referred to the epigastric region.