428 CLINICAL APPLIED ANATOMY. 



round the lower part of the loin to the front of the abdomen, and 

 thence to the testicle, groin or inner side of the knee, following 

 the direction of the branches of the lumbar plexus. The pelvis 

 of the kidney and the ureter, where the pain originates, are 

 particularly associated with the eleventh and twelfth dorsal and 

 first lumbar segmental areas. (Fig. 20-23, p. 226.) Cutaneous 

 hypersesthesia may be expected to occur in these areas during 

 and after a paroxysm of colic. The skin of the scrotum, which 

 is supplied from sacral segments, does not become tender, but 

 the testicle does ; the implication of the latter may be explained 

 by the presence of filaments of the genito-crural nerve in the 

 tunica vaginalis, which is said to be the only serous membrane 

 supplied by a spinal sensory nerve. 



The connexion of the vagus nerve with the renal plexus may 

 account for the nausea and vomiting which may be associated 

 with renal calculi. 



The anterior and posterior arterial vascular areas of the kidney 

 are separated by the pelvis and do not anastomose. As a rule 

 three-quarters of the kidney belong to the anterior vascular area 

 and the remaining quarter to the posterior. The direction of the 

 axes of the posterior row of calyces indicates the plane of division 

 between the two territories. The veins are not arranged in the 

 same way, but all ultimately pass to the front of the pelvis. A 

 longitudinal column of renal substance, consisting of fused 

 columns of Bertini, and bearing large vessels, intervenes between 

 the anterior and posterior sets of pyramids. In incising the 

 kidney to search for stone it is well to keep behind this column. 

 The least damage to vessels is done by an incision parallel to the 

 posterior surface of the kidney a little behind its convex border ; 

 this will pass between the two vascular territories and open the 

 posterior calyces. It should be carried into them in front of the 

 posterior row of papillae to avoid section of the collecting tubules 

 of the pyramids. 



Ureteric Calculus. There are three narrow points in the 

 ureter at which a stone is liable to become arrested. Of these 

 one is just below the renal pelvis ; the second is at the pelvic brim 



