I/O THE SURGICAL ANATOMY OF THE HORSE 



little can be done in such cases, and fatal hemorrhage is the common 

 termination. The terminal branches of the posterior circumflex artery 

 of the shoulder are very frequently involved in injuries to the outer 

 aspect of this joint, but haemorrhage in these cases may be readily 

 arrested by ligation or compression with the artery forceps, since their 

 position is not difficult to locate. 



The Brachial Artery. — As already stated, this vessel is the direct 

 continuation of the axillary artery, the name brachial being given to the 

 vessel as it crosses the tendon of insertion of the teres major muscle. At 

 first it curves slightly forwards, and then descends the brachial region in 

 an almost vertical manner by crossing obliquely the line of direction 

 of the shaft of the humerus. Just above the inner condyle of the 

 humerus the brachial artery terminates by splitting into the anterior 

 and posterior radial arteries. During its course it lies on the small 

 head of the triceps extensor cubiti muscle, and then on the bone itself. 

 In front of the artery are the coraco-humeralis and biceps muscles, from 

 which it is separated by the median nerve, which a little lower down 

 crosses the artery from before backwards. Behind the artery is its 

 satellite vein, posterior to which again is the ulnar nerve. 



The collateral branches of the brachial artery are as follows : 

 (i) The Prehumeral Artery. — This branch is also called the anterior 

 circumflex artery. It leaves the brachial artery and passes outwards at 

 right angles across the median nerve. The next part of its course is 

 across the front of the humerus between the two portions of the coraco- 

 humeralis muscle, and its terminal branches are expended in the 

 mastoido-humeralis. Its collateral branches are distributed to the 

 coraco-humeralis and biceps muscles, and a long slender branch ascends 

 on the outer aspect of the shoulder joint along the line of direction of 

 the tendon of the infraspinatus muscle. The prehumeral artery anasto- 

 moses freely with the scapulo-humeral or posterior circumflex artery. 



(2) The Deep Humeral Artery is a very large branch which leaves the 

 brachial artery just below the common tendon of insertion of the teres 



