INNOMINATE BONE. 



1.01 



ilimn, os pubis and ischium. These three poiiions meet at the aceta- 

 bulum, in the formation of which they all take part ; and the os pubis 

 and ischium also meet on the inner side of the obturator foramen. 



Fig. 88. — KlGHT Os iNNC-dlNATUM 

 FROM THE BURSAL ASPECT. (A. T. ) i 



1, anterior suijerior ; 2, anterior 

 inferior spinous process ; 3, pos- 

 terior sTiperior ; 4, posterior in- 

 ferior spinous process ; 5, crest of 

 the ilium ; 6, surface occupied by 

 tlie gluteus niediiis muscle above 

 the superior curvetl line ; above 3 

 and 4 is a rough surface to which 

 the gluteus maximus is attached ; 7, 

 surface between the superior and 

 inferior curved lines occupied by 

 the gluteus minimus ; S, groove 

 above the acetabulum for the pos- 

 terior tendon of the rectus femoris ; 

 9, superior ramus of the pubis, and 

 pectineal eminence ; 10, crest and 

 spinous process of the pubis; 11, 

 place of meeting of the descending 

 ramus of the pubis with the as- 

 cending ramus of the ischium ; 12, 

 spine ; and 13, tuberosity of the 

 ischium ; 14, cartilaginous surface 

 of the acetabulum ; 15, STOovial de- 

 Xiression and pit for the round 

 ligament ; 16, thyroid or obturator 

 foramen ; 17, greater, and 18, 

 lesser sciatic notches. 



The ilium constitutes the superior expanded portion of the bone, and 

 forms a part of the wall of the acetabulum by its inferior extremity. 

 Above the acetabulum it is limited anteriorly and posteriorly by margins 

 which diverge at right angles one from the other, and superiorly by an 

 arched thick and extensive border, 5, the crista ilii. The crest is curved 

 like the letter /, the anterior extremity pointing slightly inwards and 

 the posterior outwards ; its surface is broadest in its anterior and pos- 

 terior thirds, it is rough for the attachment of muscles, and on it may 

 be distinguished an external and internal lip and an intermediate 

 space. The anterior extremity of the crest forms a projection forwards 

 called the (interior superior spine of the ilium, and, separated from it 

 by a concave border, and placed immediately above the acetabulum, is 

 another eminence called the anterior inferior spiite : the projecting 

 posterior extremity of the crest forms the posterior superior spine, 

 and separated from it by a notch is the posterior inferior spine, below 

 which the posterior border of the bone is hollowed out into the (jreat 

 sciatic notch. The external surface, or dorsum of the ilium, concavo- 

 convex from behind forwards, presents, close to the posterior extremity 

 of the crest, a roughness of some extent, to which the gluteus 

 rnaximus muscle is attached, and is traversed by two rough arched 

 i'ines, one of which, tlte superior curved line, beginning in front, at 

 the upper border of the bone, about an inch and a half from its 



