486 THE URINARY APPARATUS. 



lodge the arteries ; the right kidney has always a special furrow for the 

 ureter. Each kidney has a circumference divisible into three borders, only 

 the internal of which offers a certain interest. This is deeply notched, to 

 form the fissure or hilm of the kidney, which lodges the vessels and nerves 

 of the organ, as well as the origin of its excretory canal. 



Weight. The kidneys vary much in weight in individuals. The right 

 is always more voluminous and heavy than the left, its average weight 

 being 27 ounces, while that of the last is 25 ounces. 



Relations. The relations of these two glands with the neighbouring 

 parts ought to be particularly examined. The right kidney corresponds, by 

 its upper face, to the great psoas muscle, the muscular portion of the 

 diaphragm, and to the last, or even the second-last rib. Its inferior face, 

 incompletely covered by peritoneum, adheres, for the greater part of its 

 extent, either to the pancreas and supra-renal capsule, or to the base of the 

 cecum, by means of a loose and abundant cellular tissue. The internal 

 border is in contact with the posterior vena cava and the small psoas 

 muscle ; the anterior, with the base of the right lobe of the liver and the 

 lobule of Spigel (lobus Spigelii\ through the medium of the peritoneum ; 

 the posterior border is enveloped in peritoneum. The left kidney affects, by 

 its superior face, the same connections as the right, except in its relation 

 with the second last rib. Its inferior face is almost entirely covered by 

 peritoneum, and responds, in front and inwardly, to the supra-renal capsule. 

 The internal border is margined by the aorta ; the anterior touches the base 

 of the spleen and the left extremity of the pancreas ; the posterior is, like 

 the inferior face, in contact with the serous membrane of the abdominal 

 cavity. 



Internal conformation. If a horizontal section is made of the kidney, it 

 will be found to possess a cavity called the renal pelvis, into which the urine 

 secreted by the gland flows, and at which the ureter commences. Placed in 

 the middle of the kidney, near the hilus, the pelvis is elongated from before 

 to behind, and depressed from above to below. Within it is remarked a 

 wide infundibulum, the origin of the ureter (the sinus renalis). Opposite to 

 this funnel-shaped space is a very prominent crest that runs along the whole 

 length of the external side of the pelvis, and on which are noticed the 

 orifices of the uriniferous tubes ; these, by pressing the tissue of the kidney 

 with the fingers, can be made to pour out the urine accumulated in them. 

 The renal cavity forms some very small diverticuli opposite the infundibulum, 

 the largest of which, situated before and behind the latter, are named the 

 arms of the pelvis. 



This cavity is lined by a transversely plicated mucous membrane, 

 continuous with that of the ureter, and is covered with the epithelium of the 

 uriniferous tubes which open on the border of the crest. 



STRUCTURE. The kidneys present for study in their structure : 1, An 

 enveloping tunic ; 2, Their proper tissue ; 3, A cavity named the renal pelvis, 

 into which the urine secreted in the glandular tissue flows, and which serves 

 as the origin of the ureter. 



1. ENVELOPING TUNIC. This is a fibrous membrane, intimately united 

 to the proper substance of the kidney, into which it sends a multitude of 

 prolongations, and is folded around the blood-vessels in such a manner as to 

 form sheaths, which enter with them into the organ. (Some authors 

 among them Leyh describe, in addition to this capsula propria, a thin layer 

 formed by the condensed areolar matrix of the kidney, from which it can be 

 easily torn.) 



