192 ANATOMY OF THE ABDOMEN, ETC. 



The KIDNEYS are oval-shaped organs of a deep red color, 

 and smooth surface, convex externally and concave toward 

 the vertebral column ; the concave border at its central 

 part presents a longitudinal fissure called the hilus ; at this 

 point the renal artery enters and the vein and ureter 

 emerge. 



The URETER is the excretory duct which conveys the 

 urine to the bladder ; it is of the size of a pipe-stem, except 

 at its commencement, where it is dilated and forms part 

 of what is called the pelvis of the kidney. It is of a 

 bluish-white color and of a firm fibrous texture, and is 

 lined within by a thin mucous membrane ; it passes down- 

 ward upon the psoas muscle, behind the peritoneum, 

 crosses the external or common iliac artery, and dips down 

 behind the bladder to enter it at its base. The ureter is 

 sometimes double, either in a part or the whole of its 

 length. 



The ureter should be divided midway between the kidney and the 

 Madder; then the vein and artery being cut across, the kidney may 

 be easily, and without injury, torn from its bed by the fingers. A 

 longitudinal incision along its convex margin should divide the 

 kidney in such a way that it may be opened and its interior exposed, 

 without its two halves being separated at the concave border. 



The kidney is about four inches long, two wide, and on< 

 in thickness ; it weighs about four and a half ounces. Its 

 upper extremit}^ is larger than the lower; its postcrioi 

 surface is flatter than its anterior, and it is invested with a 

 special capsule, which the nail of the thumb and fore-fingei 

 may easily detach from its surface. Internally, it is com- 

 posed of two distinct structures and an irregular-shaped 

 cavity, called the pelvis. That portion surrounding the 

 pelvis is made up of cones, six or eight in number, called 

 pyramids of Malpiglii, the apices of which are directed 

 toward the centre of the organ ; they are composed of 

 congeries of straight tubes called tubuli uriniferi. The 

 apices of the pyramids are called papillae, and are covered 

 by a thin mucous membrane, perforated by orifices, through 

 which the tubuli discharge the urinary secretion into the 

 pelvis; they are surrounded by a sort of "prepuce," so to 

 speak, also covered by a thin mucous membrane, and which 

 is called the calyx, or infundibulum, of the pyramid ; the 

 projection of the papillae into the pelvis produces the irregu- 

 larity of outline which characterizes that cavity ; the ureter 



