THE URO-GENITAL SYSTEM. 



BY A. FRANCIS DIXON. 



THE URINARY ORGANS. 



kidneys, or glands which secrete the urine, are a pair of almost symmetric- 

 ally placed organs, situated in the posterior part, of the abdominal cavity, one 

 on each side of the lower movable portion of the vertebral column. The fluid, 

 or urine, secreted by the kidneys is received into the upper expanded portions of 

 a pair of long tubes, the ureters, and by them it is conducted to the bladder, 

 which is placed within the pelvic cavity. From the bladder the urine is passed, 

 during micturition, along a passage called the urethra to the exterior. In the 

 male the urethra is a relatively long passage, and traverses the prostate gland and 

 the whole length of the penis ; in the female it is a short tube, and opens on the 

 surface just above the vaginal orifice. 



THE KIDNEYS. 



The kidney (ren), when removed from a fresh subject, presents a bean-shaped 

 contour. It is of a dark brown-red colour, and is surrounded by a thin glistening 

 capsule, the tunica fibrosa, which gives to the whole organ a uniformly smooth 

 surface. The kidney is not a solid body, but contains a cavity called the sinus 

 renalis, the opening into which, termed the hilum renale, is situated on the medial 

 and anterior part of the organ. Each kidney measures about 4J inches in length, 

 2 inches in width, and about 1 inches in thickness, and is placed so that its 

 long axis is nearly vertical. The weight of the adult kidney is about 4J 

 ounces. In the freshly removed kidney the superior and inferior ends are 

 \ smoothly rounded, and the extremitas superior or superior end is usually a little 

 more bulky than the extremitas inferior or inferior end. The margo lateralis or 

 lateral border, which is opposite the hilum, is rounded and convex, while the 

 margo medialis or medial border, on which the hilum is placed, is concave from above 

 downwards. These two borders separate the fades anterior or anterior surface 

 from the facies posterior or posterior surface of the kidney. 



The capsule, which envelops the whole organ, divides in the region of the 

 hilum into two layers, one of which is continued over the lips of the hilum 

 into the interior of the kidney, and lines the walls of the renal sinus. 

 The other layer is prolonged to form a tubular sheath for the vessels and nerves 

 of the kidney before they pass through the hilum to enter the sinus, within 

 which they break up into branches. These branches, piercing the wall of the 

 sinus, enter the substance of the kidney. The upper expanded portion of the 

 ureter leaves the sinus, through the hilum, in company with the blood-vessels and 

 nerves. 



Position of the Kidneys. The precise level of the kidney in the abdominal 

 cavity is subject to a considerable amount of variation, and, further, it is usual to 

 find a difference in the level of the right and left kidney in the same individual. 

 Most frequently the left kidney is on a somewhat higher level than the right, 

 but in many cases the kidneys are found to occupy the same level, or, the more 

 usual condition being reversed, the right kidney is a little higher than the left. 



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