56 THE SUPERIOR EXTREMITY 



is cartilaginous. During the second or third year a secondary 

 centre appears for the Capitulum and lateral part of the Trochlea, 

 and this is followed, about the fifth year, by the centre for the 

 Medial Epicondyle. At this period the distal and medial part 





FIG. 20. Elbow Joint of Boy, aged fourteen. The centres of ossification 

 in the distal extremity of the humerus are well shown. 



of the diaphysis grows distally, separating the Medial Epicondyle 

 from the rest of the Epiphysis (Fig. 17). During the eleventh 

 and twelfth years centres appear for the Lateral Epicondyle 

 and the remainder of the Trochlea. The true epiphysis consists 

 of the three lateral centres of ossification, which fuse with one 

 another at thirteen or fourteen, and it joins the shaft between 



