STRUCTURE OF THE KIDNEYS, 



529 



Fig. 232.' 



quantity of fat ; they rest on the diaphragm, on the anterior lamella of the 

 transversalis muscle, which separates them from the quadratus lumborum, 

 and on 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 against 

 it ; and it is covered in by the ascending colon and by its flexure. The 

 left kidney, 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 to- 

 wards the parietes of the abdomen ; the concave border looks inwards 

 towards the vertebral column, and is excavated 

 by a deep fissure, the hilus renalis, in which are 

 situated the vessels and nerves and pelvis of the 

 kidney; the renal vein being the most anterior, 

 next the renal artery, 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 present in its 

 interior two structures, an external or vascular 

 (cortical), and an internal or tubular (medullary) 

 substance. The tubular portion is formed of pale 

 reddish-coloured conical masses, corresponding 

 by their bases with the vascular 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 com- 

 posed of blood-vessels and of the plexiform convolutions of uriniferous 

 tubuli, and not only constitutes the surface of the kidney, but dips be- 

 tween the cones and surrounds them nearly to their apices. 



The cones or pyramids of the tubular portion of the kidney are com- 

 posed of minute straight tubuli uriniferi, of about the diameter of a fine 

 hair. The tubuli commence at the apices of the cones, and pursue a pa- 

 rallel course towards the periphery of the organ, bifurcating from point to 

 point, and separated only by minute straight blood-vessels, and a small 

 quantity of parenchymatous substance. At the bases of the pyramids the 

 tubuli collect into smaller conical fasciculi, which are prolonged into the 

 substance of the cortical portion of the kidney, and have interposed be- 

 tween them processes of the vascular structure. In the smaller pyramids 

 the fasciculi separate into their component tubules, w r hich, after a course 

 marked by "tortuosities, plexuses, convolutions, and dilatations," ter- 

 minate, according to Mr. Bowman, f in small round bodies, the corpora 



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

 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, con- 

 sisting of cones. 4, 4. Two of the papillae projecting into their corresponding calices 

 5. 5, 5. The three infundibula; the middle 5 is situated in the mouth of a calyx. 0. 

 The pelvis. 7. The ureter. 



( On the Structure and Use of the Malpighian Bodies of the Kidney. Philosophic*' 

 Transactions, 1842. 



45 2 1 



