THE PERITOXEUM. 



973 



the left lumbar region and is continued into the sigmoid flexure and rectum. The 

 csecum increases in length and, finding least resistance below, finally settles into 

 the rio-ht iliac fossa, dragging down a short ascending colon. 



The mesentery, seen in the loop of Fig. 592, makes a half rotation as does 

 the loop, and its anterior surface becomes posterior, as may be inferred from Figs. 

 595 and 596. 



Fig. 597 shows the arterial supply after the twist of the umbilical loop, with 

 the coeliac axis behind the stomach, the superior mesen- 

 teric artery fastening the duodenum between itself and 

 the aorta, and the inferior mesenteric coming off below. 



During this period of intestinal torsion, the stomach 

 has suffered a double change. First the stomach twists 

 around an antero-posterior axis, so its cardiac or oesoph- 

 ageal end moves to the left and downward, while its py- 

 loric end moves a little to the right and upward ; and 

 its vertical position becomes more transverse. 



Secondly, its long axis having been parallel to the 

 vertebral column, it originally presented a right and left 

 surface, supplied respectively by the right and left vagus 

 nerves. It now falls over so that its right side becomes 

 posterior and its left side anterior, and the greater curv- 

 ature becomes more inferior, and the lesser curvature 

 more superior. The vagus nerves still supply the same 

 surfaces, which have changed their positions : the right 

 nerve now goes to the posterior surface and the left one 

 to the anterior surface. 



The lower end of the oesophagus also experiences 

 the same torsion. 



The mesogastrium is modified by this rotation to 

 the right. In the anterior mesentery is the liver (Fig. 

 590), but in the adult we find it shifted to the right side 



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in the adult it is to its left. So these three antero-pos- 

 terior organs have become laterally placed, and from 



. i . , , ,. f -. i ' i 1 



right to left are hereafter found : liver, stomach, spleen, 



FlG . 597. Final disposition 



of the intestines and their vas- 



cular relati<)ns A Aorta. H. 



rior mesenteric artery. , m r . 



Branches of inferior mesenteric 



artery. (Jonneseo.) 



Chorda Dorsalis 



2Ifsoyastriitm 



Cavity of 

 reat Omentum 



FIG. 598. Wood and cloth to illustrate stom- 

 ach and mesogastrium of two layers viewed 

 from the side. (G. S. H.) 



FIG. 599. Stomach turned to right enclosing a space 

 behind it, representing the great omentum and its cavity 

 viewed from the front. (G. 8. H.) 



Again connected with this torsion of the stomach is associated the formation 

 of the great omentum. To illustrate this, carve a piece of wood to represent the 



