214 CIRCULATORY SYSTEM. 



mosis, formed by a transverse branch equal in diameter to either 

 of the trunks. The hiternal metacarpal vein accompanies the 

 artery, having that vessel situated behind and the inner small 

 metacarpal bone in front ; the external vein, the smaller and 

 deeper-seated one, also preserves the line of the splint bone on 

 the other side, but it is more inwardly placed. These veins 

 receive in their course cutaneous veins from the front of the 

 cannon, and at their origin one or two descending veins from 

 the back of the leg. There is some variety commonly found in 

 regard to the number and disposition of the anastomosing and 

 other branches at the back of the knee ; but there are ordinarily 

 two principal venous trunks, one of which ascends over the 

 inner and back part of the joint, having the artery situated 

 behind it, the other mounts close along the inner border of the 

 trapezium. As they pass the joint, these vessels receive the 

 blood from the anterior and posterior articular veins. A little 

 above this, they communicate by a short and free anastomosis, 

 and afterwards run on to form the superficial and deep-seated 

 veins of the arm. 



The superficial brachial vein (the cephalic of the 

 human subject, the plat-vein of our farriers) continues to .ascend 

 along the inner side of the radius, inclining very gradually for- 

 ward, until it has arrived at the elbow-joint; here it crosses 

 obliquely over to the front of the biceps, and pursues its ascent 

 upon that muscle, in a direction to the point of the shoulder, to 

 the inner part of which it creeps round, and afterwards plunges 

 inward to reach the jugular vein, in which it terminates. This 

 is one of the superficial veins of the arm, it being covered only 

 by the skin from its origin to its passage over the shoulder- 

 joint ; and is, as was observed before, the vein we commonly let 

 blood from. In its course, it receives divers cutaneous and 

 muscular branches, which contribute to augment its volume a 

 little ; and, besides, contracts anastomoses with the other veins 

 of the arm, among which should not be overlooked a large and 

 remarkable communication it has with the humeral vein, just 

 before it leaves the radius, through the medium of a branch that 

 runs directly upward. 



The radial veins, springing from the coalition of the 

 metacarpal veins above the knee, are two in number, and take 

 the same course as the radial artery, and a little above the 

 shoulder-joint concur with the anastomotic branch coming from 

 the superficial brachial to form the humeral vein. They receive 

 many muscular branches as they ascend, and also some anas- 

 tomosing vessels from the ulnar and superficial veins. 



The ulnar veins are divers small vessels taking the course 



