THE CONTENTS OF THE ABDOMEN. 139 



superficial fascia, the three flat abdominal muscles, the transversalis fascia, and the peri- 

 toneum. The inferior epigastric vessels should be avoided by the rule given upon page 121. 

 The following peritoneal pockets or recesses, the development of which is subject to extraordi- 

 nary variations, may occasionally become enlarged, contain portions of the intestine, and, in 

 this manner, lead to the formation of the so-called retroperitoneal hernias. 



1. Recessus duodenojejunalis, to the left of the duodenojejunal flexure. It is open an- 

 teriorly and is bounded upon the right by the ascending portion of the duodenum and upon 

 the left by the plica duodenojejunalis of the peritoneum, which contains the inferior mesenteric 

 vein [which vein, therefore, would lie in the anterior part of the neck of a hernia occurring here. 



ED.]. As a rule, it is large enough to receive the tip of the finger. It is found by reflecting the 

 transverse colon and great omentum upward and displacing the small intestine with its mesen- 

 tery to the right. 



2. Recessus ileocaecalis superior, just above the ileocecal junction. The opening of this 

 recess is directed toward the left and is bounded anteriorly by a peritoneal fold passing from the 

 mesentery of the terminal portion of the ileum, downward and toward the right to the cecum. 



3. Recessus ileocaecalis inferior, just beneath the end of the ileum. It is open toward the 

 left and is situated between the mesenteriolum of the appendix and a peritoneal fold, the plica 

 ileocaecalis, passing from the end of the ileum to the cecum. 



4. Recessus intersigmoideus, beneath the line of attachment of the sigmoid mesocolon. 

 The Kidneys. Each kidney has a superior and an inferior pole, an external convex and 



an internal concave margin, and an anterior and a posterior surface. They are situated in the 

 lumbar region to either side of the vertebral column upon the psoas major, quadratus lumborum, 

 and transversalis muscles, and upon the crura of the diaphragm in such a manner that the longi- 

 tudinal axes of the kidneys, i. e., the lines connecting the two poles, are not parallel to the verte- 

 bral column but diverge slightly as they pass downward. The transverse axis, *. e., the line 

 connecting the middle points of the two margins, is not situated in a frontal plane, but the 

 continuations of the two axes intersect at about a right angle in front of the vertebral column, 

 so that the anterior surface is also external and the posterior one is also internal. The convex 

 border is the most posterior; this is favorable for the surgeon who sometimes attacks the kidney 

 from behind, in order to open it, and, after operative procedures in its interior, sutures 

 it together again. The kidneys extend from the lower border of the eleventh dorsal vertebra 

 to the third lumbar vertebra; in two-thirds of the cases the right kidney is placed a fingerbreadth 

 lower (Plates 12 and 15). The superior pole is consequently situated in the last intercostal 

 space ; penetrating wounds in this situation may therefore involve the pleural cavity (sinus phren- 

 icocostalis) and the kidney, particularly the left kidney, which is placed somewhat higher. 

 For this reason it is also dangerous to resect the last rib in operations upon the kidney. Ab- 

 scesses of the kidney may point upward and backward, perforate the diaphragm, and rupture 

 into the pleural cavity, or even into the lung; in such a case pus from the kidney may be expec- 

 torated. Only the anterior surface of the kidney is covered by peritoneum. The posterior 

 surface is fixed to the underlying muscles by a connective tissue rich in fat, the so-called cap- 

 sula adiposa. The twelfth thoracic nerve (n. subcostalis) and the iliohypogastric nerve (from 

 the lumbar plexus) run in this fat over the posterior renal surface (Fig. 66). These nerves are 



