44 THE SUPERIOR EXTREMITY 



posterior branch runs distally behind the lateral intermuscular septum and 

 anastomoses behind the lateral epicondyle with the dorsal interosseous 

 recurrent (p. 71), which ascends under cover of the anconseus, upon the 

 supinator (s. brevis) and the annular (orbicular) ligament. It is also joined 

 by a transverse branch from the inferior ulnar collateral (anastomotic) artery. 



(c) Ligature between the Origins of the Superior and Inferior Ulnar Collateral 

 Arteries (Inferior Profunda and Anastomotic). The Superior Ulnar Collateral 

 accompanies the ulnar nerve (p. 43). The Inferior Ulnar Collateral arises 

 two inches proximal to the bend of the elbow and runs medially upon the 

 brachialis, passing behind the median nerve. It gives off an anterior branch, 

 which runs distally in the groove between the brachialis and the pronator 

 teres to anastomose with the anterior ulnar recurrent. The artery then 

 pierces the medial intermuscular septum and joins the superior ulnar collateral 

 to anastomose, behind the medial epicondyle, with the posterior ulnar re- 

 current. 



The anastomosis detailed in (b) will also help to re-establish the circulation. 



(d) Ligature just above the Termination of the Brachial Artery. The 

 collateral circulation is the same as that described in (c). 



The Medial Supracondylar Triangle is bounded laterally 

 by the brachial artery and medially by the medial intermuscular 

 septum. Its base is formed by the medial part of the inter- 

 condylar line. The triangle contains the median nerve and 

 the epitrochlear lymph gland, the former behind the deep fascia,, 

 and the latter superficial to it. This gland is very often the 

 seat of lymphadenitis and abscess formation,, secondary to 

 septic infection of the fingers or forearm. In excision of the 

 gland the volar branch of the medial cutaneous nerve of the 

 forearm (internal cutaneous nerve) may be injured (p. 48). 



THE REGION OF THE ELBOW. 



Bony Landmarks. Both Epicondyles of the Humerns are 

 subcutaneous and are easily recognised ; the medial is the 

 more prominent, while the lateral can readily be traced upwards 

 into the lateral epicondylic ridge. The medial epicondyle is 

 the more posterior, since, when the arm is at rest by the side, 

 the humerus is medially rotated. The line joining the two 

 epicondyles is horizontal, and, in complete extension of the 

 elbow, it passes through the proximal border of the Olecranon, 

 which also is subcutaneous As the elbow is flexed, the olecranon 

 descends, till in full flexion it lies at least an inch distal to the 

 epicondyles. Between the dorsal surface of the olecranon and 

 the overlying skin there is a bursa, which is frequently infected, 



