CHAPTER XXXVI 



THE URINARY APPARATUS 



THIS consists of the kidneys ; from each a tube called the ureter leads 

 to the bladder in which the urine is temporarily stored ; from the 

 bladder a duct called the urethra 

 leads to the exterior. 



The Kidneys are two in number, 

 and are situated deeply in the lumbar 

 region of the abdomen on either side 

 of the spinal column behind the peri- 

 toneum. They correspond in position 

 to the last dorsal and three upper 

 lumbar vertebrae ; the right is slightly 

 below the left in consequence of the 

 position of the liver on the right side 

 of the abdomen. They are about 4 

 inches long, 2J inches broad, and 1^ 

 inch thick. The weight of each 

 kidney is about 4J oz. 



Structure. The kidney is covered 

 by a fibrous capsule, which is slightly 

 attached at its inner surface to the 

 proper substance of the organ by 

 means of very fine bundles of areolar 

 tissue and minute blood - vessels. 

 From the healthy kidney, therefore, 

 it may be easily torn off without 

 much injury to the subjacent cor- 

 tical portion of the organ. At the 

 hilus of the kidney, it becomes con- 

 tinuous with the external coat of the upper and dilated part of the 

 ureter (fig. 412). 



On dividing the kidney into two equal parts by a section carried 

 through its long convex border it is seen to be composed of two 



FIG. 412. Plan of a longitudinal section 

 through the pelvis and substance of the 

 right kidney, : a, the cortical sub- 

 stance ; b, b, broad part of the pyramids 

 of Malpighi ; c, c, the divisions of the 

 pelvis named calyces, laid open ; d ', one 

 of those unopened; d, summit of the 

 pyramid projecting into calyces ; e, e, 

 section of the narrow part of two 

 pyramids near the calyces ; p, pelvis 

 or enlarged portion of the ureter 

 within the kidney ; u, the ureter ; s, the 

 sinus ; h, the hilus. 



