THE HORSE. 



167 



vein has communications with the occipital 

 sinus and posterior cerebral veins, medulla 

 oblongata, and spinal marrow ; it also re- 

 ceives vessels from the deep-seated mus- 

 cles in the vicinity, and ends in the an- 

 terior vena cava, just behind the first rib. 



The axillary vein returns the blood dis- 

 tributed by the axillary artery to the va- 

 rious parts of the fore extremity ; there is a 

 superficial and deep-seated set; the former 

 run under the skin, the latter among the 

 muscles. The plantar veins are an intri- 

 cate network of small veins, and cover the 

 foot with a venous netting. The veins 

 of the sole pour their blood into the veins 

 of the lamina ; the latter increase in size 

 towards the coronet, and gradually unravel 

 themselves, so as to collect in a great many 

 branches ; these run upward, through the 

 substance of the coronary ligament, and 

 form the superficial coronary vein ; from 

 them other branches proceed and join the 

 deep coronary, and afterwards unite in 

 a single vein opposite the pastern joint. 



The veins of the frog, after ramifying in 

 the form of network over that body, ascend 

 into the heel, growing larger as they leave 

 the foot ; they make a single branch at the 

 pastern joint, then unite with the vein com- 

 ing from the laminae, thereby forming the 

 plantar vein. The plantar vein ascends, 

 unites with other vessels, and becomes 

 metacarpal. 



The metacarpal veins, two in number, 

 result from the union of the plantar ; these 

 veins pursue their course up the leg, one on 

 either side, to the back of the knee, where 

 they end in anastomosis. The internal 

 metacarpal vein preserves the line of the 

 splint bone. These vessels receive in their 

 course cutaneous veins from the front of 

 the canon, and one or two descending 

 veins from the back of the leg; it after- 

 wards forms the deep-seated veins of the 

 arm. 



The superficial brachial vein ascends 

 along the inner side of the radius to the 

 elbow-joint ; here it crosses over to the front 

 of the biceps and pursues its ascent upon 

 that muscle toward the point of the shoul- 



der, and then passes inward to the jugular 

 vein. In its course to the latter, it receives 

 numerous cutaneous and muscular branches, 

 communicates with the humeral vein, and 

 anastomoses with other veins of the arm. 



The radial veins, two in number, arise 

 from the junction of the metacarpal veins 

 above the knee ; they take the course of 

 the radial artery, and receive anastomosing 

 vessels as they ascend from the ulnar and 

 superficial veins. 



The ulnar veins (with one exception) 

 end in the common trunk of the humeral 

 vein. 



The humeral vein accompanies the ar- 

 tery ; it receives small veins from the mus- 

 cles. 



The axillary vein is the continuation of 

 the humeral, augmented by the accession 

 of the triceps vein. Its branches are, the 

 subscapular vein, and dorsalis scapular; 

 the latter terminates about midway be- 

 tween the chest and shoulder. The re- 

 maining branches of this vein are the 

 humeral thoracic, and the external thoracic ; 

 it also receives other small veins, which 

 contribute more or less to its volume. 



The pectoral vein runs the course of the 

 pectoral artery. It originates in branches 

 from the abdominal parietes, continues to 

 receive accessory vessels in its course, and 

 ascends along the inner and lower border 

 of the first rib. 



The dorso-cervical vein consists of two 

 divisions, ramifying with the dorsal and 

 posterior cervical arteries; it receives the 

 anterior intercostal vein. 



The inferior cervical vein runs down the 

 lower part of the neck in company with the 

 artery ; the principal branches are muscular, 

 though some come from the sldn and ab- 

 sorbent glands in the vicinity. 



The vena azygos ends just as the trunk 

 opens into the auricle ; it retm-ns the 

 blood from the lower intercostal veins. • 



THE POSTERIOU VENA CAVA. 



This is the corresponding venous trunk 

 to the posterior aorta, returning the blood 

 from the parietes of the abdomen and pel- 



