232 



OSTEOLOGY 



The Ala (ala oss. ilii). The ala is the large expanded portion which bounds 

 the greater pelvis laterally. It presents for examination two surfaces an external 

 and an internal a crest, and two borders an anterior and a posterior. The 

 external surf ace (Fig. 235), known as the dorsum ilii, is directed backward and lateral- 

 ward behind, and downward and lateralward in front. It is smooth, convex in front, 



Posterior 

 super 

 spine 



Posterior 

 inferior 

 spine 



Gemellus superior 

 &pine of ischium 



Oemellus inferior 



Ant. superior 

 spine 



Anterior inferior spine 



Articular capsule 

 Ligamentum teres 



Rectu-s 

 abdominis 



Pyramidalis 



Adductor 

 longus 



FIG. 235. Right hip bone. External surface. 



deeply concave behind; bounded above by the crest, below by the upper border 

 of the acetabulum, in front and behind by the anterior and posterior borders. 

 This surface is crossed in an arched direction by three lines the posterior, anterior,, 

 and inferior gluteal lines. The posterior gluteal line (superior curved line), the short- 

 est of the three, begins at the crest, about 5 cm. in front of its posterior extremity; 

 it is at first distinctly marked, but as it passes downward to the upper part of the 



