THE KIDNEYS. 



1871 



to considerable individual variation, as well as usually differing on the two sides in 

 the same subject. The right organ commonly lies somewhat lower than the left, in 

 consequence chiefly of the greater permanent volume of the right lobe of the liver. 

 Not infrequently the kidneys occupy the same level, and in exceptional cases the 

 ordinary relations may be reversed, the right lying a trifle higher than the left. 



Addison ^ found that in 30 per cent, of the subjects examined by him the right 

 kidney lay as high or higher than the left. According to Helm,' in women the kid- 

 neys lie, as a rule, about one-half of a lumbar vertebra lower than in men, this differ- 

 ence depending upon the smaller size of the vertebrae and the greater curvature of 

 the lumbar spine in the female subject. 



As a rule, the right kidney extends from the upper border of the last thoracic 

 to the middle of the third lumbar vertebra, or somewhat below the lower border of 

 the third lumbar transverse process. While always obliquely crossed by the twelfth 

 rib, the outer margin of the right kidney usually falls short of the eleventh rib. 



Fig. 1592. 



Stomach 



Aorta 



Pancrea 



Gastro-hepatie omentum 



Superior mesenteric artery 



Hepatic artery 



Transverse 

 colon 



Spleen 



Portal vein 



Transverse 



fissure 



Inferior 

 vena cava 



Liver 



Left kidney 



Perirenal fat 



Right kidney 



Cross-section of formalin-hardened body at level of first lumbar vertebra. 



Since the left kidney usually lies from 1.5-2 cin. higher than the right, its 

 upper pole is opposite the lower half of the eleventh thoracic vertebra, its lower level 

 being opposite the lower border of the second lumbar vertebra and the third transverse 

 process. Its outer margin may reach, or be crossed by, the eleventh rib ; the 

 costal relations are, however, variable and influenced by the obliquity of the ribs, 

 which is greater when the ribs are well developed than when they are. rudimentary. 

 The kidneys in young children in general lie somewhat lower than in later life. 



Fixation. — Although possessed of mobility to a limited degree, — slight depres- 

 sion and elevation probably normally accompanying respiratory movements, — the 

 kidneys have a fairly fixed position. The maintenance of the latter has been 

 variously ascribed to the support afforded by the peritoneum, the perirenal con- 

 nective tissue and fat, the blood-vessels, and the surrounding organs, all of which 

 during life may contribute to this end. Gerota, however,' has shown that, apart 

 from the blood-vessels and, especially in children, the suprarenal bodies, the peri- 

 toneum and adjacent organs may be removed without materially lessening the fixation 

 of the kidneys, the latter receiving support particularly from their peculiar and inti- 

 mate relations with the subperitoneal tissue. This, in the vicinity of the kidney, 



' Journal of Anatomy and Physiology, vol. xxxv., 1901. 

 ^ Anatom. Anzeiger, Bd. xi., 1896. 

 ^ Archiv f. Anat."und Entwick., 1895. 



