ABDOMINAL CAVITY 359 



the submucous tissue. They are most numerous close to the 

 pylorus, and gradually disappear about two inches beyond it. 



Lien (Spleen). The spleen is a solid organ which lies deeply 

 in the left part of the costal zone, and is altogether out of 

 sight in the undisturbed condition of the viscera, but it is 

 exposed when the stomach is removed. It lies very obliquely 

 in the abdominal cavity, its upper end being much nearer the 

 median plane and much further back than its lower end. 

 Its long axis is directed from above downwards and laterally, 

 and also to some extent forwards. For the most part it lies 

 in the left hypochondrium, but its upper end extends 

 medially beyond the left lateral plane, so that fully a third 

 of the organ is situated in the epigastric region. 



The spleen, when properly hardened in situ, has the shape 

 of an irregular tetrahedron. Its four surfaces are the dia- 

 phragmatic, the gastric, the renal, and the colic. The 

 diaphragmatic surface, which is the most extensive of the 

 four, is convex. It looks backwards and laterally ; it rests 

 against the posterior part of the diaphragm, to the curvature 

 of which it is adapted, and it is separated by the diaphragm 

 from the lower parts of the left lung and pleura, and from 

 the ninth, tenth, and eleventh ribs. 



The three remaining surfaces, the gastric, the renal, and 

 the colic, look towards the interior of the abdomen ; they 

 are all in close apposition with the adjacent viscera and, 

 consequently, they are grouped together as the visceral 

 surfaces. Of the three the gastric is the largest, the colic is 

 usually the smallest, and all three are concave. They are 

 separated from one another by three ridges which radiate from 

 an inconspicuous prominence called the intermediate angle, 

 which forms the apex of the tetrahedron (Fig. 169). One of 

 the ridges, the margo intermedius, forms a salient border, which 

 ascends from the intermediate angle to the superior angle, 

 and separates the gastric from the renal surface. The 

 superior angle is curved forwards on itself to some extent, 

 and approaches close to the left suprarenal gland. A 

 second and much shorter ridge passes backwards from the 

 intermediate angle, and terminates at the posterior angle ; 

 it separates the renal surface from the colic surface. The 

 third ridge, which is often rounded and indistinct, passes 

 forwards from the intermediate angle to the anterior angle, 

 and separates the gastric from the colic surface. 

 ir23 b 



