THE ILIUM 



93 



THE ILIUM 



The ilium (Os ilium) is the largest of the three parts. It is irregularly triangu- 

 lar and presents two surfaces, three borders, and three angles. 



The gluteal surface (Facies glutaea) faces upward, backward, and outward. It 

 is wide and concave in front, narrower and convex behind. The wide part is crossed 

 by the curved gluteal line (Linea gluta?a), which extends from the middle of the 

 inner border toward the external angle. This surface gives attachment to the 

 middle and deep gluteal muscles. 



The pelvic surface (Facies pelvina) faces in the opposite direction; it is convex, 



Fig. 60. — Oss.\ Cox.\rum of M.^^re, Dors.\l View. 

 O.il., Ilium; O.p., pubis; O.is., isciiium; A.o.i., wing of ilium; C.o.i., .shaft of ilium; Cr.o.i., anterior 

 border (crest) of ilium; /, obturator foramen; 2, acetabulum; 3, internal angle of ilium; 4, external angle of 

 ilium; o, gluteal line; 6, psoas tubercle; 7, 8, acetabular and symphyseal branches of pubis; 9, 10, acetabular 

 and symphyseal branches of ischium; 12, lesser sciatic notch; 13, ischial arch; 14, great sciatic notch; 15, sym- 

 physis pelvis; /7, ilio-pectineal eminence; /5, anterior borders of pubic bones; 75, posterior gluteal line. (Struska, 

 Anat. d. Haustiere.) 



and consists of two distinct parts. The inner triangular part (Pars articularis) 

 is roughened for ligamentous attachment, and bears an irregular facet, the auricu- 

 lar surface (Facies auricularis), for articulation with the sacrum. The outer quad- 

 rilateral part (Pars iliaca) is in general smooth. It is crossed by the ilio-pectineal 

 line (Crista iliopectinea), which begins below the auricular surface and is continued 

 on the shaft of the bone to join the anterior border of the pubis. The line is inter- 

 rupted by furrows for the iliaco-femoral vessels, and below these it bears the psoas 

 tubercle (Tuberculum psoadicum), which gives attachment to the psoas minor mus- 

 cle. The iliacus muscle is attached to the surface external to the ilio-pectineal line. 



