part of part of Homo sapiens tetrapod frontal bone zone of bone organ glabella of frontal bone 2026-03-19T00:00:00Z A zone of bone organ forming the smooth, slightly convex midline prominence of the frontal bone located between the two superciliary arches, just above the nasion. It is the most anterior projecting point of the forehead in the median plane. David Osumi-Sutherland