THE REGION OF THE ELBOW 63 



of the humerus is weakened by the grooving of the trochlea and 

 by the olecranon and coronoid fossae. It has to withstand the 

 force transmitted through the forearm from falls upon the hand, 

 and in consequence fractures in this situation are very common. 



In children, the injury may take the form of a Separation 

 of the Distal Epiphysis of the Humerus. In adults, the 

 supracondylar fracture of the shaft frequently radiates through 

 one of the fossae into the joint, giving rise to the so-called T- or 

 Y-shaped fracture. 



The medial epicondyle may be fractured without other 

 injuries. It is displaced distally and forwards by the attached 

 flexor and pronator muscles. Sometimes the line of this fracture 

 is oblique and includes a portion of the trochlea in addition, 

 consequently involving the joint. Through faulty apposition 

 the medial epicondyle may be displaced proximally, changing 

 the transverse axis of the trochlea (p. 51), and subsequently 

 leading to the condition of cubitus varus. 



This injury may involve the ulnar nerve, causing neuritis 

 and progressive paresis of the muscles which it supplies (p. 104). 

 Occasionally the symptoms do not appear till many years later, 

 and evidence of injury, of which there is often no history, is 

 obtained only by the X-rays. 



Injury to the lateral epicondyle may lead in the same way 

 to the condition of cubitus valgus (see Carrying Angle, p. 51). 



Fracture of the Olecranon Process. The small, proximal 

 fragment usually includes the proximal half of the semilunar 

 notch, and, consequently, the joint cavity of the elbow is 

 involved (Fig. 18). The swelling, which is partly due to the 

 violence, is increased by haemorrhagic extravasation into the 

 joint, and it may press upon the superficial veins, producing 

 cedema of the forearm and hand. There may be little or no 

 separation of the fragments, in which case they are kept in 

 position by the periosteum, the ulnar collateral (internal lateral) 

 ligament of the elbow, the anconaeus, and the common ulnar 

 aponeurosis. When wide separation occurs, the proximal 

 fragment is drawn proximally and backwards by the triceps, 

 and difficulty is experienced in keeping the ends in good 

 apposition. On this account the surgeon frequently has recourse 

 to the operation of wiring. The fragments can be brought 

 together by two wires one vertical, the other transverse 

 without interfering with the articular surface (Fig. 23). 



Fracture of the Neck of the Radius is a rare accident, 



