38 THE ARMY HORSE. 



into four branches, the right and left external and internal 

 iliacs, which supply blood to the hind extremities. 



The internal iliacs are short thick trunks which soon break up 

 into several branches to the muscles of the hind quarters. The 

 external iliacs^ with their continuations, are the main arteries 

 of the hind legs. Each, as previously stated, begins below the 

 last lumbar vertebra, curves obliquely outward and downward, 

 giving off branches, and, near the head of the femur, receives 

 the name of femoral artery. 



The femoral artery is the arter}^ of the thigh. Just above the 

 back of the stifle joint it divides into two branches, the anterior 

 and posterior tibial., the latter supplying the back part of the 

 gaskin and hock Avith nourishment, while the former winds 

 forward between the tibia and fibula to the fore part of the leg, 

 gaining it midway between the stifle and the hock. At the 

 hock it passes obliquely outward, crossing the joint, and becomes 

 the great metatarsal artery at the upper and outer part of the 

 metatarsus. The great metatarsal passes under the small splint 

 bone and gains the back part of the cannon, then, passing down 

 the leg, it divides just below the fork of the suspensory liga- 

 ment into two branches, the external and internal digitals., 

 which will be studied later. 



The involuntary muscles of the heart receive their blood sup- 

 ph' from two small arteries, right and left coronary., which 

 branch off at the beginning of the common aorta. 



Veins. 



Veins are usually found accompanying the arteries of the 

 body and bearing similar names; there are several important 

 exceptions, three of which will be here noted, namel}^, the 

 anterior oena cava, jugular, and posterior vena cava. 



The anterior vena cava is the large, short vein, formed by 

 numerous branches, returning the blood from the head, the 

 neck, the fore leg, and part of the chest. It is located in the 

 front part of the thorax, below the trachea, and between the 

 right and left pleura', and empties into the right auricle. 



The jugular veins (right and left) are the largest branches of 

 the anterior vena cava and collect the blood from the head and 

 neighboring parts. Just below and back of the lower jaw 

 they approach the carotid arteries and run down the neck in 

 their company. Each jugular is outside of the corresponding 



