92 



Bones of the Upper Extremity. 



Muscle furrows 



114. The Hio-lit 115. The Right 

 R a d i u H , Radius, lx a d ins, Radius, 



from before. from behind. 



The upper extremity 

 of the radius forms the 

 head, Capitulum radii, which 

 has a somewhat depressed ar- 

 ticular surface ; the constricted 

 portion below the head is the 

 neck. Below the 'latter is the 

 t ub er o s i ty , Tu berositas radii 

 (for the insertion of the M. 

 biceps). 



The three sided shaft 

 turns its most marked bor- 

 der, the Crista radii, toward 

 the same border of the ulna. 



The broad lower e x- 

 t r e in i t y has an articular 

 surface inferiorly , and a 

 second smaller, semilunar ar- 

 ticular surface, the sigmoid 

 cavity of the radius or Inci- 

 sura seinilnnaris radii, at the 

 inner side, where it articulates 

 with the Capitulum ulnae,. From 

 the external surface, the one 

 opposite the sigmoid cavity, 

 the s ty 1 o i d process, Pro- 

 ccssus styloideus' radii, projects. 



The radius articulates 

 with four bones: the humerus, 

 the ulna, the scaphoid and semi- 

 lunar bones. 



