474 



DISSECTION OF THE ABDOMEN. 



Fig. 163. 



more pointed. The position with respect to the spinal column has been 

 before detailed (p. 435). 



On the anterior surface the viscus is rounded, but on the opposite sur- 

 face it is generally flattened. 



The outer border is convex ; but the inner is excavated, and is marked 

 by a longitudinal fissure, hilum. In the fissure the vessels are thus placed 

 with respect to one another : The divisions of the renal vein are in front, 



the ureter is behind, and the branches of the 

 artery lie between the two. On the ves- 

 sels the nerves and lymphatics ramify ; and 

 areolar tissue and fat surround the whole. 

 Opposite the fissure is a hollow in the inte- 

 rior of the kidney, named sinus, in which 

 the vessels and the duct are contained be- 

 fore they pierce the renal substance. 



Dissection. To see the interior it will 

 be necessary to cut through the kidney 

 from the inner to the outer border ; and to 

 remove the loose tissue from the vessels, 

 and from the divisions of the excretory 

 duct. The hollow or sinus containing the 

 bloodvessels now comes completely into 

 view. 



The interior of the kidney fig. 163) ap- 

 pears on a section to consist of two diffe- 

 rent materials, viz., of an external granular 

 or cortical part ; and of internal, darker 

 colored, pyramidal masses, which converge 

 towards the centre. But these unlike- 

 looking parts are constructed of urine tubes, 

 though with a different arrangement. 



The pyramidal masses (d) (pyramids of 

 Malpighi), are twelve or eighteen in num- 

 ber, and converge to the sinus of the kid- 

 ney. The apex of each mass, which is free 

 from cortical covering, is directed to the 



sinus, and ends in a smooth, rounded part, named mamilla or papilla (c). 

 In it are the openings of the urine tubes, which are about twenty in num- 

 ber, some being situate in a central depression and the others on the sur- 

 face ; and it is surrounded by one of the divisions (calyx) of the excretory 

 tube. Occasionally two of the masses are united in one papillary termina- 

 tion. The base is embedded in the cortical substance, and is resolved into 

 bundles of tubes which are prolonged into the cortical covering. 



Each pyramidal mass is constructed of uriniferal tubes (tubes of Bellini) 

 which open below at the apex of the papilla (fig. 164, a) ; and the cut 

 surface has a grooved appearance indicatory of its construction. If the 

 mass is compressed, urine will exude from the tubes through the apertures 

 in the apex. 



The cortical or investing part (fig. 163, e) forms about three-fourths of 

 the kidney ; it covers the pyramidal masses with a layer about two lines 

 in thickness, and sends prolongations between the same nearly to their 

 apices. Its color is of a light red, unless the kidney is blanched ; and its 

 consistence is so slight that the mass gives way beneath the finger. In 



SECTION THROUGH THE KIDNEY, BHOW- 

 ISGTHE MEDULLARY AND CORTICAL 

 PORTIONS, AND THE BEGINNING OF 

 THK URETER (Henle). 



a. Ureter. 



b. Pelvis of the ureter. 



e. Calyx of the excretory tube. 



d. Pyramidal portions. 



e. Cortical portion of the kidney. 



