1 88 THE SUPERIOR EXTREMITY 



It supplies, therefore, all the muscles on the lateral and 

 dorsal aspects of the forearm, with the exception of the 

 brachio-radialis and the extensor carpi radialis longus, which 

 derive their nerve-supply directly from the radial nerve (O.T. 

 musculo-spirat}. The anconseus derives its main nerve of supply 

 from the radial nerve, but not infrequently it also obtains a 

 second twig from the dorsal interosseous nerve. 



Dissection. Detach the anconaeus from its origin and throw 

 it towards its insertion in order to display the course of the 

 dorsal interosseous recurrent artery. Trace that artery to the 

 back of the lateral epicondyle, and then examine the arterial 

 anastomosis around the elbow- joint. 



Anastomosis around the Elbow Joint. The series of 

 inosculations around the elbow should now be reviewed as a 

 whole. A distinct inosculation will be found to take place 

 upon both the anterior and posterior aspect of each epi- 

 condyle of the humerus. Behind the lateral epicondyle the 

 interosseous recurrent artery joins the posterior branch of the 

 profunda brachii artery: anterior to the same epicondyle the 

 anterior branch of the profunda brachii artery communicates 

 with the radial recurrent On the medial side of the joint the 

 anterior and posterior ulnar recurrent arteries ascend respectively 

 in front of and behind the medial epicondyle ; the former 

 anastomoses with the anterior branch of the inferior ulnar 

 collateral artery^ and the latter with the posterior branch of 

 the same artery and with the superior ulnar collateral artery, 



In this account of the anastomosis around the elbow joint 

 only the leading inosculations are mentioned. Rich net- 

 works of fine vessels are formed over the olecranon and the 

 two epicondyles of the humerus. One very distinct and fairly 

 constant arch requires special mention. It is formed by a 

 branch which crosses the posterior aspect of the humerus, 

 immediately proximal to the olecranon fossa, and connects 

 the posterior branch of the profunda brachii artery with 

 the posterior branch of the inferior ulnar collateral artery. 



Terminal Branch of the Arteria Interossea Volaris. 

 The so-called perforating branch of the volar interosseous 

 artery is a vessel of some size, and is, really, the main con- 

 tinuation of the artery. It perforates the interosseous mem- 

 brane about 50 mm. proximal to the distal end of the radius, 

 and is at once joined by the dorsal interosseous nerve. It 

 descends, with the nerve, in the most medial groove on the 



