20 OF THE PELVIS. 



while movable upon each other; however, they at length coalesce; 

 but, in most women, the bone, as a whole, loses its power of moving 

 upon the sacrum only at a very advanced age. 



§. III. Of the Coxal bone (os coxalium). 



13. The bone of the ilium, the hip bone, the nameless bone, or 

 more properly, as was long ago indicated by Celsus, the coxal bone, 

 situated between the femur and the sacrum, alone forms the two an- 

 terior and lateral thirds of the pelvis. 



14. Of an irregular quadrangular shape, looking as if strangulated 

 at its middle, and twisted in two opposite directions, the coxal bone 

 exhibits two surfaces and four edges. 



15. On its internal or pelvic surface, which is divided into two 

 nearly equal portions, we distinguish, above, a large excavation 

 called the internal iliac fossa, which is filled by a muscle of the same 

 name; behind, an articular surface, of a semilunar shape, called the 

 articular facette; still farther behind, certain rugosities, similar to 

 those observed on the edge of the sacrum, with which they unite. 



On its inferior half, and posteriorly is seen a plane, almost trian- 

 gular surface, which corresponds to the cotyloid cavity, and to the 

 body of the ischium; in its middle, the sub-pubal opening; in front, 

 the internal face of the pubis, and of the ischio-pubal ramus. 



16. A semicircular edge, thick, smooth, and rounded posteriorly, 

 thin and sharper in front where it terminates in the crista of the 

 pubis, an edge which forms the greatest part of the superior strait, 

 and unites these two halves of the pelvic surface of the coxal bone. 



17. Its external or femoral surface exhibits, on its upper half, 

 what is called the external iliac fossa, filled by the three glutei mus- 

 cles; below, the sub-pubal hole, the external face of the ischium and 

 ischio-pubic ramus; in the middle, the cotyloid cavity. 



18. Its upper edge, or the iliac crista, thicker both posteriorly and 

 anteriorly than in the middle, twisted like an italic s, divided by the 

 anatomists into an external lip, an internal lip, and an interstice, 

 for more conveniently describing the attachment of muscles, termi- 

 nates in front, by the anterior-superior spine of the ilium, and behind, 

 by the postero-superior spine of the ilium. 



19. Its lower edge presents three portions; superiorly, an oval 

 surface for the articulation of the pubes; inferiorly, the tuberosity of 

 the ischium; and in the middle, the edge of the ischio-pubic ramus, 

 turned somewhat outwards. 



20. On its anterior edge, proceeding from above, downwards, 

 and from the ilium towards the pubis, we remark the superior iliac 

 spine; a small semilunar notch; the inferior iliac spine; the groove 



