712 THE BLOOD-VASCULAR SYSTEM OF THE OX 



The radial artery is the smaller of the two terminal branches of the median. It 

 descends on the flexor carpi radialis, passes over the medio-volar surface of the 

 carpus, and is continued as the medial deep volar metacarpal artery. At the distal 

 end of the forearm and at the carpus it furnishes branches to the retia carpi. An- 

 other branch (A. met. perforans proximalis) runs outward between the suspensory 

 ligament and the large metacarpal bone, passes through the proximal foramen of 

 the bone, and unites with the dorsal metacarpal artery; before passing through the 

 foramen it detaches the middle deep volar metacarpal artery (A. met. volaris prof. 

 III.). This descends on the volar face of the metacarpal bone, receives an anasto- 

 motic branch from the medial deep artery, and concurs in the formation of the deep 

 volar arch above the fetlock. The medial deep volar metacarpal artery (A. met. 

 volaris prof. II.) descends along the medial part of the volar surface of the large 

 metacarpal bone and is continued as the medial volar proper digital artery. At the 

 distal part of the metacarpus it is connected by a transverse branch with the middle 

 deep volar metacarpal artery, and similarly with the volar common digital, forming 

 with the latter the superficial volar arch. 



The ulnar artery, the larger of the two divisions of the median, descends under 

 cover of the flexor carpi radialis without giving off any large branches in the fore- 

 arm. It passes through the carpal canal and continues along the medial side of the 

 deep flexor tendon as the volar common digital artery (A. met. volaris superficialis 

 III.). At the distal third of the metacarpus this vessel is joined by a branch from 

 the medial deep volar metacarpal artery, forming the superficial volar arch. Near 

 this another branch of the common digital (or of the medial digital) passes around 

 the lateral border of the flexor tendons to the posterior face of the metacarpal bone 

 and concurs with the deep volar metacarpal arteries in the formation of the deep 

 volar arch. A branch from the arch (A. met. perforans distalis) passes forward 

 through the distal foramen of the metacarpal bone and joins the dorsal metacarpal 

 artery which descends from the rete carpi dorsale in the dorsal metacarpal groove. 



The volar common digital artery (A. metacarpea volaris superficialis III.) 

 passes into the interdigital space and divides into two volar proper digital arteries, 

 which descend along the interdigital surfaces of the chief digits and pass through 

 the foramina at the proximal part of the interdigital surfaces of the third phalanges, 

 enter the cavities in these bones, and ramify in a manner similar to the correspond- 

 ing vessels in the horse. The volar common digital detaches a branch (A. inter- 

 digitalis perforans) which passes forward through the upper part of the interdigital 

 space and anastomoses with the dorsal metacarpal artery. 



The volar proper digital arteries (or the common digital) give off, in addition to other col- 

 laterals, branches which correspond to the arteries of the digital cushion of the horse. These 

 pass to the bulbs of the claws and anastomose with each other and with the medial and lateral 

 digital arteries, forming an arch from which numerous branches are distributed to the corium 

 of the hoofs. 



The dorsal metacarpal artery (A. met. dorsalis III.) is a small vessel which 

 arises from the rete carpi dorsale, descends in the groove on the dorsal face of the 

 metacarpal bone, and is joined by the distal perforating metacarpal artery from 

 the deep volar arch to constitute the dorsal common digital artery. This vessel 

 (A. digitalis communis dorsalis III.) divides into two dorsal proper digital arteries. 



The medial volar digital artery (A. digiti III. medialis) is the continuation of the 

 medial deep volar metacarpal artery. It descends on the medial side of the medial 

 digit and terminates at the bulb of the claw by anastomosing with the corresponding 

 volar proper digital artery. It gives off a branch to the rudimentary digit and 

 forms a transverse anastomosis behind the first phalanx with the volar common- 

 digital or its medial division. 



The lateral volar digital artery (A. digiti IV. lateralis) arises from the deep volar 



