Bones of the Upper Extremity. 



91 



The superior ex- 

 tremity of the ulna shows 

 a deep excavation, the grea- 

 ter sigmoid cavity, Cavitas 

 siymoidea major } which is 

 bounded above by the ole- 

 c r a n o n process (also 

 called Processus anconaeus), 

 and below by the c o r o n o i d 

 process. On the outer side 

 of the latter is the lesser 

 sigmoid cavity, Cavitas sig- 

 moidea minor, for articulation 

 with the head of the radius ; 

 below this is the tuberosity, 

 Tuberositas ulnae (for the in- 

 sertion of the M. brachialis 

 anticus). 



The shaft has three 

 surfaces and three bor- 

 ders, of which latter the 

 one turned toward the radius 

 is called the Crista ulnae. 



The inferior ex- 

 tremity is called h e a d, 

 Capitulum ; this has an ar- 

 ticular facet, part of which 

 is turned downwards, and 

 part outwards to be received 

 into the sigmoid cavity of 

 the radius. From the back 

 part of the head the sty- 

 lo i d process, Processus 

 styloideus ulnae projects. 



112. The Right 113. The Right 



The ulna articulateswith m m ^ jj( 



the huraerus and the radius. 



from before. from behind. 



