Chapter 63: Abdominal Oesophagus & Stomach

Abdominal Oesophagus & Stomach academic overview provides a comprehensive exploration of the abdominal oesophagus and the stomach, beginning with the short, intra-abdominal portion of the oesophagus, which typically measures 1 to 2.5 cm long, positioned slightly to the left of the midline before ending at the gastro-oesophageal junction. This segment is functionally anchored by the phrenico-oesophageal ligament, a structure composed of elastin- and collagen-rich connective tissue that limits mobility through the oesophageal hiatus and is critical for surgical mobilization. Key innervation for this area is provided by the anterior and posterior vagal trunks, both of which surgeons must meticulously identify during procedures such as fundoplication to prevent complications like gastro-paresis. Crucially, the normal anti-reflux mechanism is maintained by a specialized high-pressure zone (HPZ) formed by the intrinsic circular smooth muscle of the distal oesophagus, reinforced by the extrinsic fibers of the respiratory diaphragm's right crus. Failure of this system is associated with gastro-oesophageal reflux and hiatal hernia, which is typically of the sliding type. The stomach itself is the widest segment of the alimentary canal, situated primarily in the upper abdomen, and is responsible for nutrient storage, mechanical food breakdown, protein digestion, and intrinsic factor secretion. Anatomically, the stomach is divided into the fundus, body, cardia, pyloric antrum, and pylorus. Internally, the mucosa forms gastric folds (rugae), though along the lesser curvature, these form the ‘magenstrasse,’ which facilitates the quick passage of liquids to the pylorus. Microstructurally, the gastric wall is characterized by glands that secrete various substances: parietal (oxyntic) cells in the principal glands produce gastric acid and intrinsic factor, chief (peptic) cells generate pepsin and lipase, and G cells in the pyloric glands secrete gastrin. The stomach's rich arterial supply originates mainly from the coeliac trunk, forming extensive intramural anastomoses via the left and right gastric arteries (lesser curvature) and the left and right gastro-omental arteries (greater curvature), providing resistance against ischemia and allowing for surgical conduit creation. Venous drainage mirrors the arterial supply, contributing to the hepatic portal system, notably through the left gastric vein, which represents a significant site for oesophageal varices development in cases of chronic portal hypertension. Lymphatic drainage follows vascular paths to nodes, including the left gastric and coeliac groups, necessitating careful classification during oncology treatments, defined by D1, D2, and D3 lymphadenectomies. Furthermore, specialized cells called interstitial cells of Cajal regulate gastric motility, which involves the proximal stomach handling storage and accommodation, while the distal stomach executes strong contractions to grind food and regulate passage through the pyloric sphincter.