Abdominal oesophagus and stomach

Embryology

The organs that are derived from the primitive foregut extend from the base of the tongue to the region of the ampulla of Vater. Their corresponding arterial supply comes from the coeliac axis with generous collateral circulation provided by branches of the thyrocervical trunk, aorta and superior mesenteric artery. The oesophagus and stomach represent the proximal enteric organs of the foregut; the duodenum, liver and pancreas constitute the remainder. Unequal growth of the walls of the stomach leads to rotation and elongation on the left side of the stomach, which ultimately becomes the greater curvature.

Surgical anatomy

The abdominal oesophagus is the distal continuation of the thoracic oesophagus and is 1–3 cm in length. It crosses the oesophageal hiatus at the level of the tenth to eleventh thoracic vertebrae and lies posterior to the left lateral segment of the liver, anterior to the left crus of the diaphragm. It is tethered to the oesophageal hiatus by the phreno-oesophageal ligamentous complex ( Fig. 58.1 ). The superior layer of the phreno-oesophageal ligament is continuous with the subpleural endothoracic fascia above the diaphragm and is thicker and contains more elastin than its inferior counterpart; it runs cranially and obliquely to fuse firmly with the wall of the oesophagus. The inferior layer is an extension of the subperitoneal transversalis fascia below the diaphragm and is thin and only loosely attached to the oesophagus.

The stomach is the first entirely intra-abdominal organ of the gastrointestinal tract and it is the widest part of the tract ( Video 58.1 ). It is a hollow, comma-shaped organ located in the left upper abdomen, and can greatly increase in volume when distended. It is tethered by the abdominal oesophagus and oesophageal hiatus proximally, the duodenum distally, and the lesser and greater omenta along its lesser and greater curvatures, respectively. The concave, medial border of the stomach is the lesser curvature. It follows a gentle curve from the medial side of the oesophagus as it terminates in the cardia of the stomach. Approximately three-quarters of the way along the lesser curvature, the stomach makes a sharp turn to the right at the angular incisure (incisura angularis). A line at this point, transecting the stomach perpendicular to its long axis, defines the transition from the body of the stomach to the pyloric antrum. The lesser omentum, consisting of the hepatoduodenal and hepatogastric ligaments, is a double layer of peritoneum that runs from the portal plate to the lesser curvature and proximal duodenum. The distal portion of the hepatogastric ligament is thinner and more translucent. The inferior edge of the lesser omentum is the anterior boundary of the omental foramen. The convex surface of the stomach is the greater curvature, which runs from the fundus (the proximal dome of the stomach that lies to the left of the intra-abdominal oesophagus) to the pylorus. The greater omentum, a double layer of peritoneum consisting of the gastrocolic, gastrosplenic and gastrophrenic ligaments, is draped along the greater curvature of the stomach. The gastrocolic ligament contains the gastro­epiploic vessels that run in close proximity to the greater curvature of the stomach; the gastrosplenic ligament contains the short gastric vessels, and the gastrophrenic ligament is largely avascular.

The long axis of the stomach runs from superior to inferior and from left to right, directly overlying the lesser sac, which is not generally a large space. The stomach therefore directly overlies the pancreas and the major vasculature of the retroperitoneum. Laterally, it is in contact with the hilum of the spleen and the diaphragm; the posterior aspect of the liver is often anterior and to the left.

Vascular supply and lymphatic drainage

Arterial supply

The arterial supply of the stomach is predominantly via the coeliac trunk, directly from the left gastric artery, and indirectly from the gastroepiploic, right gastric and short gastric arteries. This redundant blood supply and rich submucosal plexus allow division of multiple feeding arteries without compromising gastric viability. The most striking example of the richness of the blood supply is in the setting of an oesophagectomy with reconstruction by a gastric conduit ( Figs 58.2–58.4 ). After this operation, the sole blood supply of the gastric conduit is the right gastroepiploic artery: this single vessel can provide an adequate blood supply for the neo-oesophagus, together with its cervical anastomosis. However, the rich blood supply of the stomach also means that ligation of the gastric vasculature is often a futile manœuvre to control bleeding from a gastric ulcer. The left gastric artery is the smallest of the three branches of the coeliac trunk. It ascends briefly towards the left crus, contributes branches to the intra-abdominal oesophagus, and then turns inferiorly where it follows the lesser curvature to anastomose eventually with the right gastric artery within the lesser omentum. With the surgeon's left palm facing posteriorly over the abdominal aorta, gentle downward traction can facilitate exposure of the left gastric artery for easy ligation. This manœuvre also facilitates palpation of the splenic and hepatic arteries, which must be preserved. It is important to remember that accessory or replaced left hepatic arteries may arise from the left gastric artery. When present, the vessel can be palpated as it crosses the lesser omentum on its way to the porta hepatis. The right gastric artery can arise from the hepatic artery proper or from any of the surrounding blood vessels. It travels retrogradely over the first portion of the duodenum in the lesser omentum, and ascends along the lesser curvature to anastomose with the left gastric artery. The left and right gastroepiploic vessels run along the greater curvature of the stomach. The right gastroepiploic artery arises from the gastroduodenal artery just inferior to the first portion of the duodenum, runs in close proximity to the greater curvature and anastomoses with the left gastroepiploic artery at the midportion of the greater curvature: this area may often be appreciated during surgery as an indentation of the perigastric fat. The short gastric vessels arise from the distal splenic artery and supply the fundus and left superior portion of the greater curvature. If traction is applied to the spleen or stomach, the surgeon must be conscious of avoiding traction injury to these vessels; their meticulous ligation is required during splenectomy to avoid haemorrhage.

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