222 SURGICAL APPLIED ANATOMY. [Chap. xin. 



Dislocation of the radius forwards. Tins 

 may be due to direct violence to the bone from behind, 

 or to extreme pronation, or to falls upon the extended 

 and pronated hand. The anterior, external, and 

 annular ligaments are torn. There would seem to be 

 a lack of evidence in support of Hamilton's statement 

 that " sometimes the anterior and external lateral 

 are alone broken, the annular ligament being then 

 sufficiently stretched to allow of the complete disloca- 

 tion." The biceps being relaxed, the pronators act, 

 and the limb is either pronated, or assumes a position 

 midway between pronation and supination. Some 

 stretching of the supinator brevis would probably 

 modify the amount of pronation. A difficulty in the 

 reduction is often due to the torn annular ligament 

 coming between the head of the radius and the 

 humeral condyle. 



Fractures of the lower end of the humerus. 

 These are : (1) A fracture just above the condyles ; 



(2) "the T-shaped fracture" involving the joint; 



(3) fractures of the internal, and (4) of the external 

 condyle ; (5) fracture of the internal epicondyle ; and 

 (6) separation of the lower epiphysis. 



All these fractures are more common in the 

 young. 



1. The fracture "at the base of the condyles," as 

 it is sometimes called, is usually situate a little above 

 the olecranon fossa, where the humeral shaft begins 

 to expand. It is commonly transverse from side to 

 side, and oblique from behind downwards and forwards. 

 It is generally the result of a blow inflicted upon 

 the extremity of the elbow. Probably the tip of 

 the olecranon driven sharply against the bone acts 

 Like the point of a wedge, and takes an important 

 share in the production of the fracture. The lower 

 fragment, together with the bones of the fore-arm, is 

 generally carried backwards by the triceps, and 



