104 



Anatomy of the Rabbit. 



excluded through the development in the acetabular depression of .a 

 small triangular element, the os acetabuli. Although completely coalesced 

 in the adult condition, and showing but few traces of their original 

 separation, the three chief elements are nevertheless described as if distinct. 



The ilium (os ilium) is the anterior, 

 also somewhat dorsal, portion of the 

 bone ; that part extending forward from 

 the acetabulum. It comprises a basal 

 portion, the body (corpus oss. ilium), 

 which includes the anterior portion of 

 the acetabulum and the cylindrical part 

 of the bone in front of it, and an ex- 

 panded portion, the iliac wing (ala oss. 

 ilium), for muscle attachment and 

 articulation with the sacrum. The body 

 is somewhat triangular in section, its 

 surface being divided into three areas, 

 which are respectively medial, or sacral, 

 ventrolateral, or iliac, and dorso-lateral, 

 or gluteal. The corresponding borders 

 are respectively ventral, or pubic, lateral, 

 or acetabular, and dorsal, or ischial. 

 The acetabular border terminates a short 

 distance in front of the acetabulum in 

 an abruptly truncated projection, the 

 inferior anterior spine (spina anterior 

 inferior) . The ischial border forms the 

 anterior half of a long depression of the 

 dorsal surface of the coxal bone, the 

 greater sciatic notch (incisura ischiadica 

 major). The pubic border presents on 

 its medial side a faint, ridge-like eleva- 

 tion, the iliopectineal line (linea iliopect- 

 inea), which connects the sharp anterior 

 border of the pubis with the articular 

 surface for the sacrum. 



The wing of the ilium forms a shovel- 

 like expansion, the natural position of 

 which is almost sagittal. Its lateral 

 surface provides a fairly extensive area 

 for the origin of the gluteal muscles. 

 Its medial surface is a muscle surface 

 only in its anterior portion, the posterior 

 portion being occupied by the roughened 

 auricular surface (facies auricularis), 

 for connection with the sacrum. The dorsal margin is thin and straight. 

 Posteriorly, where it is associated with the greater sciatic notch, there 

 is a small projection, the inferior posterior spine (spina posterior inferior) 

 Anteriorly it passes by a broad angle into the anterodorsal margin of 



Fig. 40. 

 coxal bone: 

 pubis; a., _ 



Lateral surface of the left 

 IL, ilium; IS, ischium; P, 

 acetabulum; a.i., iliac wing; 

 body of ilium; c.is., body of ischium; 

 c p., body of pubis; cr., iliac crest; e.i., 

 iliopectineal eminence; f.a., acetabular 

 fossa; f.o., obturator foramen; i.a., 

 acetabular notch; i.mi., lesser sciatic 

 notch; i.rni., greater sciatic notch; l.i., 

 iliopectineal line; p.l., lateral process of 

 ischial tuberosity; r.i.i., inferior ramus of 

 ischium; r.i.p., inferior ramus of pubis; 

 r.s.i., superior ramus of ischium; r.s.p., 

 superior ramus of pubis; s.a.i., inferior 

 anterior spine of the ilium; s.a.s'., superior 

 anterior spine; s.i., ischial spine; s.p., 

 symphysis pubis; s.p.i., inferior posterior 

 spine; t.i., ischial tuberosity; t.p., pubic 

 tubercle. 



