part of part of Homo sapiens innominate bone zone of bone organ auricular surface of ilium of os coxa 2026-03-19T00:00:00Z A zone of bone organ forming the ear-shaped articular surface on the posteromedial aspect of the ilium of the os coxa (innominate bone), covered by fibrocartilage and articulating with the corresponding auricular surface of the sacrum to form the sacroiliac joint. David Osumi-Sutherland