1268 THE UKO-GENITAL SYSTEM. 



Traces of the superficial lobulation of the kidney, present in the foetus and young child, are 

 often retained in the adult. 



Horse-shoe kidney is not an infrequent abnormality. In these cases the two kidneys are 

 united at their inferior ends, across the median plane, by a connecting piece of kidney substance. 

 The amount of fusion between the two kidneys varies much ; it is sometimes very complete, 

 while in other cases it is but slight, the connexion being chiefly composed of fibrous tissue. 



In very rare cases the kidney appears to be almost entirely surrounded by peritoneum and to 

 be attached to the abdominal wall by a kind of mesentery, enclosing the vessels and nerves passing 

 to the hilus. The condition is believed to be congenital. 



Not very infrequently one or both kidneys are found at a much lower level than usual, and 

 occupying a position in the iliac fossa or the pelvic cavity. This condition, when congenital, is 

 associated with an arrest in the normal change in position, relative to surrounding structures, 

 which the kidney experiences during development. In such cases the kidney does not 

 receive its blood -supply from usually placed renal arteries, but from vessels which arise from 

 the lower end of the aorta, or from the iliac, or the middle sacral artery. These congenitally 

 abnormally situated kidneys do not usually possess the typical outline of the normal organ, but 

 vary much in shape, and the hilum is often directed downwards or backwards, and not medially. 



In some mammalian animals, such as the bear, the ox, the porpoise, etc., the kidneys are 

 composed of a number of completely isolated lobes, each of which corresponds to one papilla, its 

 pyramids and surrounding cortex ; while in others, such as the horse, the fusion of the lobes is 

 more complete even than in the human kidney, and a single mass represents the united papillae. 



THE DUCT OF THE KIDNEY. 



The duct of the kidney is called the ureter, and begins above in a thin-walled 

 funnel-shaped expansion called the pelvis renalis, which is placed partly within 

 and partly outside the sinus of the kidney. Towards the level of the inferior 

 end of the kidney the part of the pelvis which lies outside the sinus diminishes 

 in calibre, and forms a tube-like duct, the ureter, which conveys the urine to the 

 bladder. 



Pelvis of the Kidney. Within the sinus of the kidney the pelvis lies among 

 the larger renal vessels. It is formed by the junction of two, or more rarely three, 

 thin-walled tubes, the calyces maj ores, each of which has a number. of branches. 

 These latter, called calyces renales minores, are short, and increase in diameter as 

 they approach the sinus wall, to which they are attached. Their wide, somewhat 

 funnel-like ends enclose the renal papillae, and receive the urine, which enters them 

 through the foramina papillaria. The calyces are usually about eight in number, 

 one calyx sometimes surrounding two or even three papillae. The portion of the 

 pelvis that lies outside the kidney has in front of it, in addition to the renal 

 vessels, on the right side, the descending part of the duodenum, and on the left side, 

 a part of the pancreas and sometimes the duodeno-jejunal flexure (Fig. 979). 



Ureter. The ureter is the vessel which carries the urine from the pelvis of the 

 kidney to the bladder. It is a pale-coloured thick-walled duct with a small lumen. 

 While in situ it has a total length of about ten inches, and lies throughout its 

 whole course in the subperitoneal tissue, behind the peritoneum, to which it is 

 closely connected. In its superior part the ureter lies in the abdominal cavity, and 

 in its inferior part in the pelvis minor (Figs. 983 and 988). 



The normal ureter, in the flaccid condition, measures after its removal from the body eleven 

 to fourteen inches. 



The pars abdominalis, or abdominal portion of the ureter, about five or five and 

 a half inches in length, is directed downwards and slightly medially, and lies upon 

 the psoas major muscle. Certain structures are related to the ureters in a similar 

 manner on each side of the body ; for instance, the abdominal portion of each ureter 

 is crossed very obliquely, on its anterior aspect, by the internal spermatic vessels, 

 and behind each ureter the genito-femoral nerve passes downwards and laterally 

 (Fig. 983). Other structures are related to the duct of the right or left side 

 alone ; on the right side, the descending part of the duodenum lies in front of the 

 upper part of the ureter, and the line of attachment of the mesentery crosses it lower 

 down, just before the ureter enters the cavity of the pelvis minor. On the left 

 side the line of attachment of the mesentery of the pelvic colon crosses the ureter. 



Crossing the common iliac, or the external iliac artery, the ureter enters the 

 pelvis minor. The left ureter usually crosses the common iliac artery, and the right 



