470 



THE URINARY ORGANS OF THE HORSE 



upper parts of the last two or three ribs and the tip of the first lumbar transverse 

 process. The dorsal (or superior) surface (Facies dorsalis) is strongly convex; 

 it is related chiefly to the diaphragm, but also to a small extent posteriorly 

 to the psoas muscles. In well hardened specimens, especially those from thin 

 subjects, impressions of the last two ribs and the tip of the first lumbar transverse 

 process are usually visible. The ventral (or inferior) surface (Facies ventralis) is 

 in general slightly concave, and is related to the liver, pancreas, caecum, and right 

 adrenal ; it either has no peritoneal covering, or only a narrow area externally is so 

 covered. The internal border (Margo medialis) is convex and rounded; it is 

 related to the right adrenal and the posterior vena cava. It presents about its 

 middle a deep notch, the hilus (Hilus renalis) ; this is bounded by rounded 

 margins, and leads into a space termed the renal sinus (Sinus renalis). The ves- 



FiG. 375. — Diagram of Position and Dorsal Relations of Kidneys of Horse. 



Areas of direct relations are inclosed by continuous lines; parts of skeleton which overlie the kidneys but are not in 



contact with them are indicated by dotted lines. L.I-III , lumbar transverse processes. 



sels and nerves reach the kidney at the hilus, and the sinus contains the pelvis or 

 dilated origin of the ureter. The external border (Margo lateralis) is rounded, 

 and is thinner than the internal one. It consists of two parts, anterior and 

 posterior, which meet at an external angle; the anterior part fits into the renal 

 impression of the liver. The duodenum curves around the external border. The 

 anterior extremity (Extremitas cranialis), thick and rounded, lies in the renal 

 impression of the liver. The posterior extremity (Extremitas caudalis) is thinner 

 and narrower. 



The left kidney (Ren sinister) is bean-shaped. It is considerably longer and 

 narrower than the right one, and is situated nearer the median plane and further 

 back, so that the hilus of the left kidney is about opposite to the posterior extremity 

 of the right one. It lies usually under the upper part of the last rib and the first 

 two or three lumbar transverse processes. Tlu^ dorsal surface is convex, and is 



