The stomach is a sac-like dilatation of the digestive tube intervening between the oesophagus and the intestine.

Its general shape is piriform, being broad and thick toward the left and narrow and thin toward the right, and its upper margin, known as the lesser curvature, is short and concave, while its lower one, the greater curvature, is long and convex. To the curvatures the peritoneum is attached, and blood-vessels pass along them. The region at which the oesophagus enters is known as the cardia and is situated on the upper border of the stomach at the left end of the lesser curvature, and the junction with the intestine, known as the pylorus, occurs at the right extremity of the stomach.

There may be recognized an anterior and a posterior wall, both of which are convex and separated from each other by the curvatures, and three chief gastric subdivisions: the cul-de-sac to the left of the cardia, the fundus; the body; and the pyloric portion.

The portion of the stomach adjacent to the pylorus is frequently separated from the body of the viscus by a slight constriction, and its cavity is known as the pyloric antrum. The pylorus itself appears upon the external surface of the stomach as a slight circular constriction, but upon the internal surface it takes the form of a circular fold of no great height which is known as the pyloric valve. In the pyloric region the lesser curvature becomes convex and the greater concave, since the stomach curves upward in this situation.

The greater portion of the stomach is situated in the left half of the body; the pyloric portion only passing to the right of the median line, so that but about one-sixth of the entire organ lies within the right half of the body. The main portion of the stomach is in the left hypochondriac region, the pylorus is in the epigastric region, although in the distended state the viscus also occupies more or less of the mesogastric region. The fundus is the highest portion of the stomach, being situated above the cardia, which in turn is higher than the pylorus, and the lowest portion of the viscus is the most curved portion of the greater curvature; consequently the longitudinal axis of the stomach passes obliquely from above downward and from left to right.

The fundus is in relation with the left leaflet of the diaphragm, with the spleen, and with, the left lobe of the liver, the latter structure covering the cardia, the lesser curvature, and part of the pylorus. The pylorus is in contact with the quadrate lobe of the liver and the gall-bladder, and is continuous with the duodenum. The great omentum is attached to the greater curvature, which is also in relation with the transverse colon, while behind lies the pancreas, separated from the stomach by the bursa omentalis, as well as the left kidney and the left suprarenal body.

With reference to the skeleton the stomach is situated at the level of from (the tenth or) the eleventh to the twelfth thoracic vertebra. The cardia is in front of the tenth or eleventh thoracic vertebra and behind the insertion of the seventh costal cartilage into the sternum. The pylorus is at the right border of the twelfth thoracic vertebra.

The size of the stomach varies greatly according to its degree of distention or contraction; a completely emptied and contracted stomach, relatively infrequent in the cadaver, looks very small and simulates intestine, while the greater curvature of a markedly distended viscus may extend downward to the navel. During marked distention the stomach also undergoes a rotation upon its longitudinal axis so that the greater curvature assumes a more anterior position. The average length of the stomach is 25 to 30 centimeters, its average width 12 to 14 centimeters, and the average thickness of its wall (which likewise varies greatly with the degree of distention) 2 or 3 millimeters.

The serous peritoneal covering of the anterior wall is furnished by the greater peritoneal cavity, while that of the posterior wall comes from the bursa omentalis. The other constituents of the gastric wall are the muscular coat, the submucous coat, and the mucous coat. The latter differs in structure in the pyloric portion from the mucosa in other parts of the stomach.

From Human Anatomy (1909) by DR. Johannes Sobotta (1869-1945) Professor of Anatomy in the university of Wurzburg.