376 ABDOMEN 



whilst the medial border is concave, and looks medially and 

 forwards. 



The kidneys present many changes in form, according to 

 the amount and the kind of pressure which is exerted upon 

 them by contiguous viscera. In most cases, however, and 

 on both sides, there is on the anterior surface of the organ 

 a point of maximum convexity a place where the kidney 

 substance is raised in the form of a marked prominence or 

 bulging. Above and below that eminence the anterior surface 

 falls away towards each extremity, in the form of an inclined 

 or sloping plane of greater or less obliquity. The impressed 

 districts indicate pressure exercised on the anterior surface 

 of the kidney in two directions, and the intervening eminence 

 is the result of the pressure and counterpressure. The char- 

 acteristic appearance is more constant and better marked in 

 the case of the left kidney. 



Upon the upper part of the anterior surface of the left 

 kidney are placed the left suprarenal gland, the stomach, 

 the spleen, and the pancreas. They exercise, collectively, a 

 downward and backward pressure, chiefly through changes in 

 the condition of the stomach. Upon the lower part of the 

 left kidney the counterpressure is produced by the intestinal 

 canal, which, as a rule, presses upwards and backwards. 



Resting upon the upper part of the right kidney is the 

 liver, whilst in contact with the lower part is the colon. 

 The colon presses on the kidney in an upward and back- 

 ward direction. To that pressure the liver offers a passive 

 resistance, except perhaps in the case of the slight influence 

 which it conveys in a downward direction from the diaphragm, 

 and in a backward direction from the anterior abdominal 

 wall. 



The pressure and counterpressure, which produce so 

 marked a conformation of the anterior surface of each kidney, 

 must exercise also an important influence in maintaining the 

 organ in its place, and securing it in that part of the abdominal 

 cavity in which it lies. Still, it is doubtful if the influences 

 have so potent an effect on the right as on the left side. 

 The right kidney is embedded to a greater or less extent in 

 the liver, and the pressure of the liver no doubt exerts an 

 influence in fixing the kidney in position. 



Ligaments fixing the kidney to the abdominal wall are 

 described, and it is easy to demonstrate that the exlra-peri- 



