174 THE SURGICAL ANATOMY OF THE HORSE 



The following branches are given off by the posterior radial artery : 



1. ^rr/a/A/r branches to the elbow joint. These leave the posterior 

 radial at the upper extremity of the radius. 



2. A large number of small muscular branches, which are distributed 

 particularly to the muscles which lie on the back of the radius. 



3. The Interosseous Artery of the Forearm. — This is a very long vessel, 

 which is frequently also of considerable calibre. It leaves the posterior 

 radial artery just below the humero-radial articulation, and then takes a 

 course outwards through the radio-ulnar arch, to reach which it 

 crosses the back of the radius beneath the flexor perforans muscle. It 

 then descends the forearm in the groove formed outwardly between the 

 radius and ulna, where it is concealed by the extensor suffraginis muscle. 

 It terminates at the carpus by contracting anastomoses with branches of 

 the anterior radial artery in the manner already described. 



The interosseous artery of the forearm gives off a number of branches 

 immediately after leaving the radio-ulnar arch. These are distributed to 

 the elbow joint and to the extensor metacarpi magnus, extensor pedis, 

 and extensor suffraginis, and a long slender branch from this vessel 

 appears from beneath the extensor pedis muscle and splits up into a 

 number of small branches which are distributed to the skin covering the 

 front of the knee, whilst in the radio-ulnar arch it gives off the nutrient 

 artery to the radius. 



4. Immediately above its point of division the posterior radial artery 

 detaches a branch which passes obliquely downwards and outwards 

 beneath the flexor metacarpi medius to anastomose with the termination 

 of the ulnar artery, and thus assist in the formation of the supracarpal arch. 



The posterior radial artery is in intimate relationship to the median 

 nerve at the seat of median neurectomy. Should the artery be 

 accidentally severed the proximal end at times becomes retracted 

 beneath the posterior superficial pectoral muscle out of the reach 

 of the operator. When a complication of this kind arises a vertical 

 incision should be made in the muscle and skin in line with the 



