THE DIAPHRAGM. 193 



opens from the general cavity of the pelvis, and their 

 mucous surfaces are continuous. The external, or cortical 

 portion of the kidney, surrounds the bases of the pyramids, 

 and penetrates irregularly between them under the name of 

 the columns of Bertin; it is composed of the tubuli con- 

 voluted among minute vascular ramifications. 



The kidney is a very vascular organ and receives its blood 

 through the renal artery, a large branch of the aorta, 

 affording an excellent illustration of the law that the size 

 of an artery is in proportion, not to the size of the viscus 

 which it is distributed, but to the activity of its func- 

 >ns. The renal vein empties into the inferior vena cava ; 

 id the nerves, which are abundant, are received from the 

 Mini plexus, this being derived from the solar plexus and 

 lesser splanchnic nerve. The large upper extremity, 

 flattened posterior surface, together with the relative 

 *ition of the vessels at the hilus permit the right kidney 

 be distinguished from the left after their removal from 

 e body ; the renal vein is the most anterior, the artery 

 is behind the' vein, and the ureter posterior to them both. 



The kidneys not unfrequently present deviations from 

 their normal shape and position ; sometimes they are united 

 into one body across the vertebral column, forming what 

 is called a horse-shoe kidney ; occasionally one is wanting. 

 They may be found placed much lower in the lumbar 

 region than usual, and have even been found in the pelvis. 

 They are usually firmly fixed in their positions, but in 

 certain instances a degree of mobility has been noticed, 

 appreciable by palpation during life, and constituting what 

 is called a floating kidney. 



THE DIAPHRAGM. 



To get a good view of the diaphragm, a large block is to be placed 

 under the loins in such a way as to elevate the base of the thorax. 

 The peritoneum must be thoroughly removed from its surface; and if 

 the thorax has not yet been opened, it can be readily stripped off by 

 the forceps and fingers. 



The DIAPHRAGM is a muscular plane separating the abdo- 

 men from the thorax; it arises from the sternum by short 

 and separated fibres, which leave a triangular interval 

 between them, covered only by the peritoneum on one side 

 and the pleura on the other ; from the superior border and 

 internal surface of the last six ribs by serrations which 

 IT 



