450 



HEALTH AND DISEASE 



the latter it divides into two: (1.) The small Metacarpal Artery. (2.) The 



large Metacarpal Artery. The former, 

 superficially placed at first on the 

 inner side of the knee, dips down 

 behind the head of the canon-bone. 

 It crosses to the outer side by pass- 

 ing between the suspensory and the 

 subcarpal ligament. Here it anasto- 

 moses with a branch from the supra- 

 (=1 v/v-\\v\ V /-/^ik/ ■ carpal arch to form the subcarpal 



I ^ m rK\ /'^y/iK / ■ t firch, which then proceeds to give oflF 

 the anterior and posterior interosseous 

 arteries, which supply blood to the 

 structures behind and in front of the 

 canon -bone, to the bone itself, to its 

 periosteum or covering, and to the 

 fiexor tendons. 



The large metacarpal artery de- 

 scends on the inner side and some- 

 what in front of the flexor tendons 

 until it reaches the sesamoid bones, 

 where it divides into two parts, the 

 internal and external digital arteries. 

 These vessels pursue a downward 

 course over the fetlock -joint, giving 

 off" branches before and behind to 

 the tissues in the region of the pas- 

 tern, and finally, entering the foot, 

 they break up into a number of 

 vessels and supply the frog, the coro- 

 nary cushion, the sensitive laminae, 

 the coffin-bone, and other parts con- 

 tained within the hoof. This artery 

 is situated between the plantar nerve 

 behind and the internal metacarpal 

 vein in front. 



Cephalic Artery.— This vessel, 

 as we have previously pointed out, 



is a branch of the right axillary and runs forward beneath the trachea 



until it reaches the entrance to the chest, where it divides into a right 



and left carotid artery. 



Fig. 193.— Diagram of Circulation 



A, A, Posterior Vena Cava. B, Anterior Vena Cava. 

 C, Pulmonary Artery. D, Hepatic Veins. K, Vena 

 Porta. F, Renal Vein. G, Spermatic Vein. 



H, Posterior Mesenteric Vein. ' Pulmonary Vein. 



' Anterior Aorta. ', * Posterior Aorta. ^ Splenic 

 Artery. « Hepatic Artery. 7 Castric Artery. 



' Anterior Mesenteric Artery. ^ Renal Artery. 



^'' Spermatic Artery. " Posterior Mesenteric Artery. 

 L.K., Left Kidney. R.K., Right Kidney. DIA., Dia- 

 phragm. R.L., Right Lung. L.L., Left Lung. 

 R.V., Right Ventricle. L.V., Left Ventricle. 

 STOM., Stomach. sp., Spleen. 



