224 SURGICAL APPLIED ANATOMY. [Chap. XIIL 



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 sixteenth year. Thus, after the age 

 of sixteen the growth of the bone must depend upon 

 the activity of the upper epiphysis, which does not 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 the 

 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 epiphysis before twenty. Since the epiphyseal 

 line is almost wholly within the capsule, it follows 

 that but little displacement, other than a slight 

 movement backwards, is consequent upon the separa- 

 tion of the mass. 



Fractures of the olecranon are commonly due 

 to direct violence, and in a few cases to severe indirect 

 violence applied to the lower end of the humerus or 

 upper end of the ulna. Instances of fracture by 

 muscular action are few, and open to some question. 

 The fracture is most commonly met with about the 

 middle of the process, just where it begins to be 



