part of part of Homo sapiens rib 1 surface groove costal groove of first rib 2026-03-19T00:00:00Z A surface groove running along the inferior border of the body of the first rib that lodges the intercostal nerve and vessels. In the first rib this groove is less pronounced than in typical ribs because the first rib is nearly horizontal and broad, with its superior surface facing upward rather than medially. David Osumi-Sutherland