part of part of Homo sapiens innominate bone zone of bone organ arcuate line of ilium of os coxa 2026-03-19T00:00:00Z A zone of bone organ forming a smooth, rounded ridge on the medial surface of the ilium of the os coxa (innominate bone), continuing the pelvic brim from the sacral promontory toward the iliopectineal eminence and demarcating the boundary between the greater and lesser pelvis. David Osumi-Sutherland