CIRCULATORY APPARATUS. 87 



ferior articular surface of the humerus, where it terminates in the 

 anterior and posterior radial arteries. 



It is in relation to the median nerve on the outside and the 

 coraco-radialis on the inside. 



Its branches are 



1. Prehumeral or anterior circumflex of shoulder. 



To shoulder joint and muscles of upper humeral region, anasto- 

 mosing with posterior circumflex. 



2. External collateral of elbow. 



To muscles in vicinity of elbow joint, where it anastomoses 

 with anterior radial. 



3. Internal collateral or ulnar. 



To internal border of arm and forearm, to carpus, anastomo- 

 sing with posterior radial, and accompanying the ulnar nerve and 

 vein. It sends branches to muscles, to elbow joint and humerus. 



4. Coraco-radial. 

 To muscle. 



ANTERIOR RADIAL. 



The smaller of two branches of humeral extends along front 

 of radius to front of carpus, where it splits up into smaller branches, 

 which supply the articulation, and anastomose with posterior 

 radial and interosseous. It gives off branches also to elbow joint 

 and muscles. 



POSTERIOR RADIAL. 



The larger of two subdivisions of humeral, passes to side on 

 internal ligament of elbow, along inner side of radius, to its in- 

 ferior portion, where it divides into the common interosseous, 

 metacarpal and collateral artery of the cannon. 



The branches in its course are to elbow and muscles of forearm. 



INTEROSSEOUS OF FOREARM. 



Arises near radia-ulnar arch, and passes along groove between 

 ulnar and radius. Gives off branches to the elbow, anti-brachial 

 muscles, and terminates at the carpus by numerous anastomoses. 



