THE STOMACH. 1617 



in contact and lubricated with a thin layer of serous fluid, secreted by the membrane, 

 by which friction between the organs and movable surfaces is reduced to a minimum. 



The serous membrane, consisting of the endothelium and the tibro-elastic tunica 

 propria, is attached to the subjacent fgisciae of the abdominal wall and the organs by 

 a layer of subperitoneal tissue^ an areolar stratum forming a more or less intimate 

 connection between the serous coat and the structures which it covers. 



The relations and attachments of the peritoneum observed in the adult are in 

 some places entirely different from those existing in early life ; hence the history of 

 the changes occurring during development is essential for understanding the complex 

 relations found at later periods. 



PLAN OF THE DIGESTIVE TRACT BELOW THE DIAPHRAGM. 



The subdiaphragmatic digestive tube is divided into the stomach, the small intes- 

 tine, and the large i7itestine. The small intestine is subdivided into the duodenum and 

 the Jejuno-ileum. The former of these is an imperfect ring or horseshoe-shaped 

 portion from 25-30 cm. (10-12 in.) long, all of which, except the first inch or two, 

 lies on the posterior abdominal wall behind the peritoneum in the adult ; then comes 

 something over 6 m. (usually about 21.5 ft. ) of intestine thrown into folds by its 

 attachment to the free edge of the mesentery. The upper tw^o-fifths of this is called 

 the Jefuniwt and the rest the ileum ; but, as the division is arbitrary, it is better to 

 speak of this portion of the small intestine as the jejuno-ileioyi, sometimes alluding 

 to the upper part as jejunum and to the lower as ileum. It ends at the right iliac 

 fossa by joining the large intestiyie, a little over 1.5 m. (usually about 5.5 ft.) long, 

 which is subdivided into the ccecimi, a blind pouch, and the colon, which is ascend- 

 ing in the right flank, transverse across the middle of the abdomen, and descending 

 on the left. This is followed at the crest of the ileum by the sigynoid flexure, a free 

 fold attached to the left of the pelvis, usually reckoned as a part of the colon, which, 

 after crossing the left sacro-iliac joint, descends in the hollow of the sacrum, to 

 become the rectum at the third sacral vertebra. The termination of the gut, passing 

 through the thickness of the floor of the pelvis, is the anal canal. Two large glands 

 — the liver and the pancreas — pour their secretions into the second part of the duo- 

 denum, from which they originally sprouted. 



The liver, the stomach, and the spleen occupy nearly all the space in the dome- 

 like upper zone of the abdomen ; the right kidney, caecum, and ascending colon 

 on the right, the left kidney and the descending colon on the left, occupy the lower 

 lateral recesses, leaving the middle space — shallow in the umbilical region and deep 

 below it — for all the rest of the intestines, except such parts as can be squeezed into 

 the preceding regions, and for the greater part of the pancreas. 



THE STOMACH. 



The stomach, the most dilated part of the digestive tube, follows the oesopha- 

 gus, lying in the upper part of the abdomen below the diaphragm on the left, and 

 passing downward and inward across the median line. In the early embryo it is a 

 tubular dilatation, but it becomes flattened from side to side and the posterior 

 border develops excessively, so that it rises above the upper opening and descends 

 below the lower one. The stomach also swings on its long axis, so that its posterior 

 border is carried to the left and the original left side to the front. The lesser curva- 

 ture is that part of the right border of the stomach between the two orifices. It is 

 straight or nearly so, and runs downward and forward to near its end, when it rises 

 and passes to the right. The lesser omentum, originally the anterior mesentery, is 

 attached to it. The greater curvat7ire is more difificult to define. It is usually 

 erroneously described as identical with the line of attachment of the greater omentum. 

 It is more accurate to define it as the line from one orifice to the other which passes 

 along the left side of the stomach and separates the anterior from the posterior 

 aspect. The greater omentum — the modified posterior mesentery — is attached to the 

 greater curvature all along except at the upper part, where it passes onto the pos- 

 terior surface. 



102 



