Anatomy

The stomach is a pyriform sac the longitudinal diameter of which is as a rule oblique in position. The larger part of the organ is situated higher up and more to the left than the smaller, which is directed to the right somewhat upward and sometimes backward. This smaller extremity terminates in the small intestine. The point at which the stomach communicates with the small intestine is called pylorus (P) and is recognizable on its outer surface by a furrow and on its inner surface by a protruding fold (valvula pylori). The communication between the oesophagus and the stomach is called the cardia (C) and is situated at the upper part. A straight line (AB) drawn in the direction of the oesophagus and prolonged through the stomach would cut off one-fourth or one-fifth of this organ to the left. This portion to the left is called the greater cul-de-sac (saccus caecus) (F) or fundus.

The volume of the stomach varies according to the condition of its contents. When tilled its long diameter measures 26 to 31 cm., the transverse diameter being 8 to 10 cm. at the fundus and much less at the pylorus. Here it measures about 2.6 cm. When the stomach is filled the anterior wall turns somewhat upward and the posterior downward (a rotation of the organ takes place).

Fig. 1. The Stomach. C, cardla.: P, pylorus: F, fundus; G, greater curvature.

Situation

The stomach lies on the left side of the body, and only one-sixth of it is situated on the right side. This includes the pylorus and the adjacent parts which lie behind the liver (lobus Spigelii). The cardia is situated in the left parasternal line, somewhat above the ensiform process; the lesser curvature lies on the left side, close to the vertebral column and runs downward and parallel with it. The greater curvature extends from the base of the gall bladder and the liver into the left hypochondriac region in which the whole of the fundus is found.

Blood-Vessels

The blood-vessels enter the stomach at its upper and lower borders and thus divide the surface of the stomach into two equal parts. These lines mark the superior and inferior margins of the stomach, the upper and lower curvature, or the lesser and greater curvature.

The Relations Of The Stomach To Neighboring Organs

The left segment of the stomach is in contact with the diaphragm above, and to the left with the spleen and the left kidney. The lesser curvature and the adjacent part of the organ are in relation with the pancreas, and the splenic artery and vein. The greater curvature and a portion of the front wall as well as the pylorus touch the liver and also the transverse colon.

Structure Of The Stomach

The stomach has four coats, the serous, muscular, areolar or submucous, and mucous. The serous coat is derived from the peritoneum and forms a thin, contain parietal or oxyntic cells, which are closely arranged in the neck of the glands. They are recognizable by being of a more or less cuboid shape and having a dark granular appearance. They are stained quite deeply with the aniline dyes. The other cells of the glands are called the principal cells, and are somewhat smaller in shape and not so dark as the parietal cells.

2. The Pyloric Glands

The mouth of the gland is quite long as compared with the tube itself. The body of the gland consists almost entirely of the principal cells. No parietal cells are to be found here, although some cells also occur which become darkly stained with osmic acid. Nussbaum considered them similar to the parietal cells of the cardiac glands. They are usually called the Nussbaum cells.

Besides these specific glands there are a number of mucous glands in the neighborhood of the pylorus.

Heidenhaiu,1 Kupffer,2 Sachs,3 and Stoehr4 have greatly contributed to our knowledge of the histology of the gastric mucosa. According to these writers, the principal cells generate the pepsin and the rennet ferments, whereas the parietal or oxyntic cells are imbued with the faculty of secreting hydrochloric acid.

Fig. 4. - A Pyloric Gland a, Mouth; o, neck: c, fundus.

1 Heidenhain: Archiv for mikrosk. Anat., vol. 6, 1870. 2Kupffer: "Epithel und Drusen dee menschlichen Magens," Munchen, 1883.

3 Sachs: Archiv f. experimentelle Patholog., vols. 22 and 34. 4Stoehr: Archiv f. mikrosk. Anat., vol. 20.