Bones of the Lower Extremity. 119 



The OS pul)is (see also Figs. 152, 153 and 155 167) helps, with its thicker 

 upper lateral portion, the corpus ossis pubis, to complete the acetabulura. Medianward 

 and somewhat in front of this portion lies a rough projection, eminentia iliopectinea, 

 formed by the os pubis and the os ilium in common. Extending forward, downward 

 and medianward from the corpus (body) is the ramus superior ossis pubis. It is 

 triangular and grows narrower from the outside in. Its posterior surface is smooth and 

 somewhat concave. Its superior surface curved so as to be slightly saddle-shaped is 

 directed at the same time obliquely lateralward and forward, is broad at its beginning 

 at the acetabulum and at the eminentia iliopectinea and is narrcw, where it ends, 

 medianward; the posterior margin of this surface, pecten ossis pubis, projects in part 

 to form a ridge, is continued behind and lateralward into the linea arcuata ossis ilium 

 and forms with it and the projection between the facies pelvina and basis ossis sacri 

 the linea terminal is of the pelvis; the anterior border arises from the incisura acetabuli, 

 is rounded, slightly concave and ends near the median plane at a small rough projection, 

 the tuber culum pubicum (0. T. spine of os pubis). The lower surface looks median- 

 ward at the same time forward and is continued lateralward into a groove, sulcus 

 obturator ius , which ascends obliquely lateralward, backward and upward on the lower 

 surface and ends on the inner surface; the sharp bony border, directed downward, by 

 which this surface and groove are bounded medianward is called the crista obluratoria 

 and presents a small projection, tuber culum obturator ium anterior. The ramus 

 superior ends medianward with an oval rough surface, facies symphyseos (0. T. sym- 

 physis pubis), for connection with the pubic bone of the other side. 



The ramus inferior ossis pubis is the narrow, flat piece of bone which extends 

 from the medial end of the ramus superior downward and lateralward and unites with 

 the upper end of the ramus inferior ossis ischii. 



The foramen obturatum (see also Figs. 152, 153, 158 and 159) is a large 

 triangularly oval opening which is bounded by the os ischii and the os pubis on all 

 sides. Its margin is everywhere sharp, except in the upper lateral angle where the 

 sulcus obturatorius is situated. The foramen obturatum is closed in the fresh pelvis 

 by a thin membrane, membrana obturatoria (see Fig. 246) whose uppermost transverse 

 bands are stretched out between the two tubercula obturatoria; the space thus left behind 

 corresponds in its course to the sulcus obturatorius and is called the canalis obtura- 

 torius (for the a. and v. obturatoria; n. obturatorius). 



