340 A MANUAL OF ANATOMY 



2. In rare cases the brachial artery divides high up into two vessels of equal 

 size, which become reunited into one trunk a little above the elbow. 



3. When a supracondylar process is present the brachial artery, along with 

 the median nerve, may descend towards the internal epicondyle until i1 

 gets below the level of the process, round which it turns forward to the 

 front of the elbow. This is the normal course taken by the artery in the 

 Felidcs, in which there is a supracondylar foramen. 



Collateral Circulation. — When the brachial artery has been 

 ligatured above the centre of the arm, the collateral circulation is 

 carried on by the superior profunda artery, which anastomoses 

 below with (i) the radial recurrent, (2) the posterior interosseous 

 recurrent, and (3) the anastomotica magna. When the artery has 

 been ligatured in the vicinity of the elbow, the inferior profunda 

 and anastomotica magna assist the superior profunda by anasto- 

 mosing with the anterior and posterior ulnar recurrent. 



Brachial Venae Comites. — These are two in number, and they 

 closely accompany the artery, one being placed on either side of 

 it. Along the course of the vessel they communicate with each 

 other across it at frequent intervals. Superiorly the external vena 

 comes crosses inwards over the lower portion of the third part of 

 the axillary artery to join the internal vena comes, and the resulting 

 trunk opens into the axillary vein near the lower border of the 

 subscapularis. 



The internal cutaneous nerve and the nerve of Wrisberg are 

 situated on the inner side of the brachial artery, the former slightly 

 encroaching upon it. The median nerve lies on the outer side of the 

 artery as low as the centre of the arm, where it passes over it, 

 and then descends on its inner side in the lower third. Instead 

 of crossing over the vessel it may pass behind it. It gives off no 

 branch in the arm, but it sometimes receives a branch from the 

 musculo-cutaneous. The ulnar nerve lies on the inner side of the 

 artery as low as the insertion of the coraco-brachialis. Here it 

 meets with the inferior profunda artery, and with it pierces the 

 internal intermuscular septum from before backwards. It then 

 descends on the inner head of the triceps to the interval between the! 

 olecranon and internal epicondyle. It gives off no branch in thai 

 arm. The musculo-cutaneous nerve, having pierced the coraco-' 

 brachialis, passes downwards and outwards between the biceps 

 and brachialis anticus. A little above the elbow it appears at the 

 outer border of the biceps, whence it descends to its cutaneous 

 distribution, already described. Before piercing the coraco- 

 brachialis, it gives off the branch to that muscle, and, as it cours 

 between the biceps and brachialis anticus, it furnishes branches : 

 them. It sometimes gives a communicating branch to the mediai 

 nerve. 



Anticubital Space. — This is the name given to the triangul 

 hollow in front of the elbow- joint. The roof of the space is fornn 

 by the integument, median basilic and median cephalic vein 

 anterior division of the internal cutaneous nerve, cutaneous pai 

 of the musculo-cutaneous nerve, deep fascia, and semilunar fascia 



