320 THE ANATOMY OF THE HORSE. 



The Renal Veins are as large in proportion as the arteries. They 

 join tlie posterior vena cava, the right vein being the shorter and 

 passing directly from the hilus, while the left crosses the lower face of 

 the aorta behind the anterior mesenteric artery. 



The Renal Plexus of nerves interlace around the artery, and enter 

 the kidney with its branches. 



The Suprarenal Capsules (Plates 44 and 47). These are two 

 small solid bodies found in close relation to the kidneys, the right being 

 between the vena cava and the inner border of the right kidney, and the 

 left between the aorta and left kidney. They have an irregular elon- 

 gated shape, and a slatey-brown colour. They ai-e highly vascular, 

 receiving branches from the mesenteric or renal arteries, and having 

 veins that enter the posterior vena cava or the renal veins. They 

 have also a rich nervous supply, receiving the suprarenal plexus — an 

 offset from the solar plexus. Tlieir substance consists of a cortical and 

 a medullary portion. Each possesses a fibrous capsule continuous with 

 an internal trabecular framework. The interspaces of these trabecule 

 contain nucleated polyhedral or branched cells, which in the medulla 

 and innermost layer of the cortex frequently enclose yellowish-brown 

 pigment. They are without ducts, and their fuAction is not well known. 



The Ureters. The ureter is the tube which conveys the urine from 

 the pelvis of the kidney to the urinary bladder. On the left side it has 

 the following course. Beginning at the hilus, it is directed backwards 

 and inwards across the lower face of the kidney to place itself at the 

 side of the aorta, over (under, in the natural position) the psoas 

 parvus muscle. Here it is crossed obliquely by the spermatic artery. 

 It next curves a little outwards, crossing over the circumflex iliac 

 artery and the artery of the cord, runs at the outer side of the 

 external iliac artery, and then crosses it very obliquely to enter the 

 pelvis. The right ureter has similar relations, except that it passes 

 at the side of the vena cava instead of the aorta. 



Directions. — Pin each ureter in position immediately behind the 

 kidney, a:id then cut it across. Remove carefully the liver, stomach, 

 duodenum, spleen, pancreas, and kidneys, by cutting the oesophagus 

 and the various ligaments, vessels, and cellular adhesions which retain 

 these organs in position. Put them in carbolic solution, or procure 

 fresh organs, to serve for the examination of their structure. In the 

 meantime proceed to dissect the sublumbar region. 



THE SURLUMBAR REGION. 



Directions. — Under this heading there will be described the abdomi- 

 nal aorta and the vena cava, witli their branches ; the inferior primary 

 branch of the last dorsal nerve, and the corresponding branches of the 

 first four lumbar nerves; the aortic plexus and gangliated lumbar cord 



