Ligaments of Elbow 265 



the artery is found between its venas comites, on the inner side of the 

 biceps tendon and close to the outer side of the median nerve. The 

 needle is passed from the inner, the nerve-side. Far to the inner side 

 is the pronator radii teres. 



Collateral circulation. If the artery be tied above the origin of 

 the superior profunda that is, close below the ending of the axillary 

 artery the superior profunda brings in blood from the well-filled 

 branches of the posterior circumflex, and thirsty muscular branches 

 help by their anastomoses with unnamed muscular branches which 

 are then given off in abundance directly or indirectly from the 

 axillary. 



If the ligature be applied below 7 the origin of the superior profunda 

 and above that of the inferior, the latter vessel will bring blood into 

 the empty trunk by its anastomosis with the former in the neighbour- 

 hood of the internal condyle. Empty muscular branches will bring 

 blood from unnamed and countless full ones ; and the anastomotica 

 magna, the posterior ulnar recurrent, and the radial and the inter- 

 osseous recurrents will also return blood from the superior profunda. 



If the ligature be below both profunda^, the collateral circulation 

 will be maintained by muscular branches, as before, and by the empty 

 anastomotica magna, the anterior and posterior ulnar recurrents, and 

 the radial and interosseous recurrent returning blood from the well- 

 filled branches of the profunda: near the elbow-joint. 



THE ELBOW JOINT 



The elbow-joint is formed by the humerus, ulna, and radius, and the 

 only movements there permitted are flexion and extension. It is a 

 pure hinge-joint. The movements of pronation and supination take 

 place at the superior radio-ulnar joint, and, though the head of the 

 radius may then be touching the capitellum of the humerus, still these 

 movements must not be considered as movements of the elbow-joint. 



As over-flexion is checked by the soft part of the fore-arm and arm 

 coming into mutual contact, and as over-extension is stopped by the 

 olecranon process impinging against its fossa in the humerus, the 

 (inferior mid the posterior ligaments are thin and mechanically un- 

 important. The former is attached to the humerus above the level of 

 the coronoid fossa, and below to the coronoid process and the orbicular 

 ligament. The posterior descends from above the olecranon fossa 

 to the border of the olecranon process. 



The internal lateral ligament is a strong triangular bundle, the 

 apex of which is attached to the internal condyle of the humerus, 

 whilst the base spreads into the borders of the coronoid and olecranon 

 processes. 



The external lateral ligament springs from just beneath the external 

 condyle, and is blended below with the orbicular ligament. 



