Surgical anatomy

Introduction

The function of the stomach is to act as a reservoir for ingested food. It also serves to break down foodstuffs mechanically and commence the processes of digestion before these products are passed on into the duodenum. The surgical anatomy must be viewed in this context.

Blood supply

Arterial supply

The stomach is richly endowed with an arterial supply on both lesser and great curves (Fig. 51.1). On the lesser curve the left gastric artery, a branch of the coeliac axis, forms an anastomotic arcade with the right gastric artery which arises from the common hepatic artery. Branches of the left gastric artery pass up towards the cardia. The gastroduodenal artery, which is also a branch of the hepatic artery, passes behind the first part of the duodenum, highly relevant with respect to the bleeding duodenal ulcer. Here it divides into the superior pancreaticoduodenal artery and the right gastroepiploic artery. The superior pancreaticoduodenal artery supplies the duodenum and pancreatic head, and forms an anastomosis with the inferior pancreaticoduodenal artery, a branch of the superior mesenteric artery. The right gastroepiploic artery runs along the greater curvature of the stomach eventually forming an anastomosis with the left gastroepiploic artery, a branch of the splenic artery. This vascular arcade, however, is often variably incomplete. The fundus of the stomach is supplied by the vasa brevia (or short gastric arteries) which arise from near the termination of the splenic artery.

Veins

In general the veins are equivalent to the arteries, those along the lesser curve ending in the portal vein and those on the greater curve joining via the splenic vein. On the lesser curve the coronary vein is particularly important. It runs up the lesser curve towards the oesophagus and then passes left to right to join the portal vein. This vein becomes markedly dilated in portal hypertension.

Lymphatics

The lymphatics of the stomach are of considerable importance in the surgery of gastric cancer and are therefore described in detail in that section (later).

Innervation

As with all of the gastrointestinal tract, the stomach and duodenum possess both intrinsic and extrinsic nerve supplies. The intrinsic nerves exist principally in two plexuses, the myenteric plexus of Auerbach and the submucosal plexus of Meissner. Compared with the rest of the gut the submucosal plexus of the stomach contains relatively few ganglionic cells as does the myenteric plexus in the fundus. However, in the antrum the ganglia of the myenteric plexus are well developed. The extrinsic supply is derived mainly from the vagus nerves, fibres of which originate in the brainstem. The vagal plexus around the oesophagus condenses into bundles which pass through the oesophageal hiatus (Fig. 51.2), the posterior bundle being usually identifiable as a large nerve trunk. Vagal fibres are both afferent (sensory) and efferent. The efferent fibres are involved in the receptive relaxation of the stomach and the stimulation of gastric motility, as well as the well-known secretory function. The sympathetic supply is derived mainly from the coeliac ganglia.