Ilium (bone) "ilis"), meaning "groin" or "flank". The ilium consists of the body and wing. Together with the ischium and pubis, to which the ilium is connected, these form the pelvic bone, with only a faint line indicating the place of union. The body () forms less than two-fifths of the acetabulum; and also forms part of the acetabular fossa. The internal surface of the body is part of the wall of the lesser pelvis and gives origin to some fibers of the obturator internus. The wing () is the large expanded portion which bounds the greater pelvis laterally. It has an
Mastoid part of the temporal bone the innermost of the mastoid cells by a very thin lamina of bone, and even this may be partly deficient. The "superior border" of the mastoid part is broad and serrated, for articulation with the mastoid angle of the parietal. The "posterior border", also serrated, articulates with the inferior border of the occipital between the lateral angle and jugular process. Anteriorly the mastoid portion is fused with the descending process of the squama above; below it enters into the formation of the ear canal and the tympanic cavity. A section of the mastoid process shows it to be hollowed out