STRUCTURE OF THE KIDNEYS. 



589 



Fig. 174.' 



closed in a quantity of fat; they rest upon the diaphragm, upon the 

 anterior lamella of the transversalis muscle, which separates them from 

 the quadnitus lumborum, and upon the psoas magnus. The right 

 kidney is somewhat lower than the left, from the position of the liver ; 

 it is in relation by its anterior surface with the liver and descending 

 portion of the duodenum, which rest upon it, and is covered in by the 

 ascending colon and by its flexure. The left Iddney, higher than the 

 right, is covered in front by the great end of the stomach, by the 

 spleen, descending colon with its flexure, and by a portion of the small 

 intestines. The anterior surface of the kidney is convex, while the 

 posterior is flat ; the superior extremity is in relation with the supra- 

 renal capsule ; the convex border is turned outwards towards the 

 parietes of the abdomen ; the concave border looks inwards towards 

 the vertebral column, and is excavated by a deep fissure, the li'dus 

 renalis, in which are situated the vessels and nerves, and pelvis of the 

 kidney ; the renal vein being the most anterior, next the renal arterv, 

 and lastly the pelvis. 



The kidney is dense and fragile 

 in texture, and is invested by a 

 proper fibrous capsule, which is 

 easily torn from its surface. When 

 divided by a longitudinal incision 

 carried from the convex to the 

 concave border, it is found to pre- 

 sent in its interior two structures, 

 an external or vascular (cortical), 

 and an internal or tubular (medul- 

 lary) substance. The tubular por- 

 tion is formed of pale reddish-co- 

 loured conical masses, correspond- 

 ing by their bases with the vas- 

 cular structure, and by their apices 

 with the hilus of the organ ; these 

 bodies are named cones (pyramids 

 of Malpighi), and are from eight to 

 fifteen in number. The vascular 

 portion is composed of blood-vessels, 

 and of the plexiform convolutions 

 of uriniferous tubuli, and not only 

 constitutes the surface of the kidney, 

 but dips between the cones and surrounds them nearly to their apices. 



If the surface of a section be examined more closely, the vascular 



* A section of the kidney, surmounted by the supra-renal capsule ; the swell- 

 ings upon the surface mark the original "constitution of the organ of distinct 

 lobes. 1. The supra-renal capsule 2. The vascular portion of the kidney. 

 3, 3. Its tubular portion, consisting of cones. 4, 4. Two of the papillae pro- 

 jecting into their corresponding calices. 5, 5, 5. The three infundibula; the 

 middle 5 is situated in the mouth of a calyx. 6. The pelvis. 7. The ureter. 



