248 SURGICAL AITLICD ANATOMY. [Ci..-^. \m. 



(Hamilton). The fragment is often displaced a little 

 upwards, backwards, and inwards, the ulna going 

 with it. 



In the fracture of the external condyle the line 

 commences also above the epicondyle and outside 

 the joint, and running downwards enters the joint 

 usually between the trochlear surface and the surface 

 for the radius. The displacement is trifling and 

 inconstant. 



On account of its insignificant size, a fracture 

 of the external epicondyle is scarcely possible. 

 Fractures of the inner epicondyle are, however, quite 

 common, the joint remaining free. This epicondyle 

 exists as a distinct epiphysis, which unites at the age 

 of eighteen, and which at any time before that age 

 may be separated from the bone by direct injury or 

 muscular violence. Owing to the dense aponeurotic 

 fibres that cover the part, much displacement of the 

 fragment is uncommon. When displacement exists, 

 it is in the general line of the common flexor muscles 

 that arise from the tip of the process. 

 - 6. The lower epiphysis. The line of this epiphysis 

 is nearly horizontal, running across the bone just 

 above the tips of the two condyles. It presents 

 several ossific nuclei, which, with the exception of the 

 nucleus for the inner epicondyle, unite with the 

 main bone about the seventeenth year. Thus, after the 

 age of seventeen the growth of the bone must depend 

 upon the activity of the upper epiphysis, which does riot 

 unite until twenty. Excision of the elbow, therefore, 

 after the sixteenth or seventeenth year, will not be 

 followed by arrest of development in the limb, even if 

 tho epiphyseal line has been transgressed by the saw. 

 Several cases are, however, reported of marked arrest 

 of growth in the limb following upon injuries to the 

 lower epiphysis before the sixteenth year, and to the 

 upper epiphjsis before twenty. Since the epipliysea] 



