402 THE UraXARY OEGAXS. 



THE URINAEY ORGANS. 



The urinary organs consist of the Icidiieys, the glands by which the 

 urine is secreted, and the ureters, Madder, and urethra, serving for its 

 reception and evacuation. As being locally connected, the sup-arenal 

 capsules are usually described along with these organs, although they 

 have no relation, so far as is known, to the secretion of urine. 



THE KIDIfEYS. 



The hidneys, two in number, are deeply seated in the lumbar region, 

 lying one on each side of the vertebral column, at the back part of the 

 abdominal cavity, and behind the peritoneum. They are on a level 

 with the last dorsal and the two or three upper lumbar vertebras, the 

 right kidney being a little lower than the left, probably in consequence 

 of the vicinity of the large right lobe of the liver. They are maintained 

 in this position by their vessels, and by a quantity of surrounding loose 

 areolar tissue, which usually contains much fat (tunica adiposa). 



The kidneys measure about 4 inches in length, 2\ inches in breadth, 

 and li inch or more in thickness. The left is usually longer and 

 narrower than the right. The weight of the kidney is usually stated 

 to be about 4A oz. in the male, and somewhat less in the female. 



According to Clendinning. the two kidneys of the male weigh on an average 

 9^ oz., and those of the female 9 oz. The estunate of Rayer is 4^- oz. for each 

 organ in the male, and 3| oz. in the other sex. Reid"s observations (made on 

 sixty-five males and twenty-eight females, between the ages of twenty-five and 

 fifty-five) would indicate a higher average weight, viz., rather more than 5^ oz. 

 in the former, and not quite 5 oz. ra the latter, — the difference between the two 

 sexes being therefore upwards of half an ounce. The 7;;-^ i-a/<'«;' weights of the 

 kidney, as deduced from the tables of Reid, are. in the adult male (160 observa- 

 tions) from 4| oz. to 6 oz., and in the adult female {li observations) from 4 oz. to 

 5^^ oz. The tables more recently published hy Peacock give still higher average 

 results as to the weight of these organs. The two kidneys are seldom of equal 

 weight, the left being almost always heavier than the right. The difference, 

 according to Rayer, is equal to about one-sixth of an ounce. The actual average 

 difference was found by Reid in ninety-three cases (male and female) to be rather 

 more than one-fourth of an ounce. The jtrojMn-tionate weight of the two kidneys 

 to the hodi/ is about 1 to 240. The s2KL'ific gmvity of the renal substance is about 

 1-052. 



The surface of the kidney is smooth, and of a deep red colour. Its 

 form is pecuHar : it is compressed from before backwards with a convex 

 outer, and concave inner border, and somewhat enlarged extremities._ 



Connections. — The anterior surface, more convex than the posterior, 

 looks somewhat outwards, and is partially covered at its upper end by 

 the peritoneum. The duodenum and ascending colon, both destitute of 

 peritoneum behind, are in contact with the anterior surface of the right 

 kidney, and the descending colon with that of the left. The front of 

 the right kidney, moreover, touches the under surface of the liver, and 

 that of the left the lower extremity of the spleen. The posterior surface, 

 imbedded in areolar tissue, rests 'firstly upon the corresponding pillar 

 of the diaphragm, in front of the eleventh and twelfth ribs : secondly, 

 on the anterior layer of lumbar fascia, covering the quadratus lumborum 



