298 CLINICAL APPLIED ANATOMY. 



ribs, its renal surface is well supported by the left kidney, and its 

 anterior extremity rests on the phrenico-colic fold. Consequently 

 the organ is enlarged in the direction of least resistance, which is 

 downwards, forwards, and inwards. If the phrenico-colic fold 

 is unusually well developed its resistance may cause the main 

 enlargement to take place in an upward direction, whilst if the 

 fold is insignificant or yields to pressure, the spleen may drop 

 directly downwards instead of being directed obliquely forwards 

 towards the umbilicus. By palpation the margin of an enlarged 

 spleen may be felt below the left costal margin. In infants the 

 spleen is felt much farther back than in adults, probably on 

 account of the greater mass of the liver in childhood. The 

 presence of the notches serves to distinguish the spleen from an 

 enlarged kidney. The latter, with which splenic enlargements 

 are often mistaken, possess a more rounded outline, and is not 

 notched. Another point of distinction is the fact that a large 

 kidney must first fill the loin, this being the position in which it 

 lies, whilst a large spleen presents itself anteriorly, for the 

 reasons mentioned above. But a very large spleen may ultimately 

 encroach upon the loin, and an enlarged kidney may ultimately 

 present anteriorly, just above the umbilicus. The spleen lies in 

 close contact with the diaphragm, and so shares in the respiratory 

 movements, unless fixed by adhesions. The kidney is also in con- 

 tact with the diaphragm, and so descends slightly on inspiration ; 

 this descent is exaggerated when the organ is enlarged. 



The intervention of the lung above, the presence of the 

 stomach and colon in the immediate vicinity, and the thickness 

 of the muscular wall of the loin, much diminish the value of 

 percussion as a means of determining splenic enlargement. 



A large spleen may exercise pressure on the diaphragm, and 

 so hamper the respiratory movements and induce partial collapse 

 of the base of the left lung. It may also exercise pressure on 

 the adjacent stomach or colon. Conversely collections of air or 

 fluid in the left pleural sac, emphysema of the lung, or intra- 

 thoracic tumours may cause depression of the spleen, and a 

 sub-diaphragmatic abscess may have the same effect. 



