THE KIDNEYS 



555 



muscles. In well-hardened specimens, especially those from thin subjects, impres- 

 sions of the last two ribs and the tip of the first lumbar transverse process are 

 usually visible.i The ventral surface (Facies ventralis) is in general slightly con- 

 cave, and is related to the liver, pancreas, cajcum, and right adrenal; it either has 

 no peritoneal covering, or only a narrow peritoneal area laterally.^ The medial 

 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 renal 

 hilus (Hilus renalis); this is bounded by rounded margins, and leads into a space 

 termed the renal sinus (Sinus renalis). The vessels and nerves reach the kidney 

 at the hilus, and the sinus contains the renal pelvis or dilated origin of the ureter. 

 The lateral border (Margo lateralis) is rounded, and is thinner than the medial one! 



Fig. 495. — Diagram of Position and Dorsal Relations of Kidneys of Horse. 



Areas of direct relations are enclosed by continuous lines; parts of skeleton which overlie the kidneys are indicated by 



dotted lines. L.I. — L.III, lumbar transverse processes. 



It consists of two parts, anterior and posterior, which meet at a lateral angle; the 

 anterior part fits into the renal impression of the liver. The duodenum curves 

 around the lateral 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 usually about opposite to the posterior 

 extremity, of the right one. It is usually ventral to the last rib and the first two 



1 The dorsal surface, being largely in contact with the diaphragm, slopes downward in front; 

 thus its anterior part is about three inches (ca. 6-8 cm.) ventral to the dorsal part of the seven- 

 teenth rib. 



^ In exceptional cases a considerable area — as much as the outer and posterior third — of the 

 surface may have a peritoneal covering. In the new-bom foal a large part is so covered; this is 

 apparently due to the small size of the caecum and the small area of attachment of its base. 



