THE KIDNEYS. 



1873 



fusion which takes place during the development (page 1704) of the large intestine 

 between the original parietal peritoneum and that covering the applied surface of the 

 primary mesentery of the descending colon ; in consequence, the left kidney is 

 invested anteriorly with a subperitoneal layer of exceptional strength. When, for 

 various reasons, the tonicity of the tissues supporting the kidney becomes impaired 

 and these structures become abnormally lengthened, the organ may acquire undue 

 mobility and suffer displacement. 



Relations. — The position of the kidneys being wholly retroperitoneal, the 

 posterior relations of both organs are chiefly muscular, since they lie closely 

 applied to the diaphragm, psoas magnus, quadratus lumborum, and the posterior 

 aponeurosis of the transversalis, the parietal fascia and perirenal areolar tissue alone 

 intervening. The inequalities in the supporting structures produce corresponding 

 modelling of the opposed renal surfaces, which is clearly distinguishable on organs 

 hardened in situ. In specimens hardened in formalin, the psoas area appears as a nar- 

 row, slightly depressed tract along the inner border ; an adjoining broader band marks 

 the area for the quadratus lumborum, beyond which the outer part of the posterior sur- 

 face rests upon the transversalis apo- 



XII rib 



Renal fascia, 



posterior 



lamella 



Transversalis 

 fascia 



Transversalis- 

 muscle 



Perirenal fat 



Iliac bone, 

 sectioned 



neurosis. The crescentic diaphragmatic Fig. i 594- 



area crosses the upper pole, the inner 

 limb of the crescent marking the con- 

 tact with the crus. In organs hardened 

 in the recumbent posture, conspicuous 

 and probably exaggerated indentations 

 show the former position of the trans- 

 verse processes of the second and third 

 lumbar vertebrce. An oblique, shallow 

 furrow crossing the kidney from the 

 upper pole outward, usually locates the 

 course of the twelfth rib. In connec- 

 tion with the posterior relations of the 

 kidneys, it is important to recall the 

 inferior limits of the pleural sacs (page 

 1859), which, where they cross the 

 twelfth rib, may descend as low as the 

 level (5f the first lumbar transverse pro- 

 cess and therefore cover the upper part 

 of the kidneys. 



The anterior relations of the 

 kidneys differ on the two sides, not 

 only as to the viscera concerned, but 

 also in the manner of their contact and 

 the consequent extent of the renal peri- 

 toneal investment. Primarily the entire 



visceral surfaces of the kidneys are covered by* serous membrane ; later this invest- 

 ment becomes only partial, in consequence of the permanent attachment which certain 

 orgaris, as the pancreas, duodenum, and colon, obtain. When these viscera undergo 

 the backward displacement incident to acquiring their final location, they are pressed 

 against the abdominal wall and the kidneys, to which they become attached by 

 areolar tissue, since the intervening opposed peritoneal surfaces lose their serous 

 character. Where the organs touching the kidneys remain covered with peritoneum, 

 the renal areas of contact retain the original serous investment. 



The right kidney is in relation with the corresponding suprarenal body, the liver, 

 the duodenum, the hepatic flexure of the colon, and, to a limited extent, usually the 

 small intestine. The right suprarenal body covers the upper pole and adjacent part 

 of the inner border of the kidney, the surface of contact being devoid of peritoneum, 

 since the organs are closely connected by areolar tissue. The liver covers the larger 

 part of the anterior surface and outer border of the kidney, which models the hepatic 

 tissue as the conspicuous renal impression seen on the inferior surface of the organ. 

 Both the liver and the kidney are invested by serous membrane, and are, therefore, 



118 



Diaphragm 



Liver 



Right 



suprarenal 



body 



Right kidney 



Peritoneum 



Renal fascia, 



anterior 



lamella 



Fibrous 

 capsule 



Colon 



Iliac fascia 



Iliacus 

 muscle 



Diagrammatic longitudinal section, showing relations of 

 supporting tissue to right kidney. {Gerota.) 



