Keel (bird anatomy) keel; and ratites (from "ratis", "raft" — referring to the flatness of the sternum), having a subtle keel structure or lacking one entirely. However, this classification has fallen into disuse as evolutionary studies have shown that many flightless birds have evolved from flighted birds. The current definition of Carinatae now includes all extant birds. Keel (bird anatomy) A keel or carina (plural carinae) in bird anatomy is an extension of the sternum (breastbone) which runs axially along the midline of the sternum and extends outward, perpendicular to the plane of the ribs. The keel provides an anchor to which a
Gray's Anatomy medicine; the anatomy of facial aging; and technical aspects and applications of diagnostic radiology. The senior editor of this book and accompanying website on ExpertConsult is Professor Susan Standring, who is Emeritus Professor of Anatomy at King's College London. The three most recent editions differ from all previous editions in an important aspect: they present anatomical structures by their regional anatomy (i.e. ordered according to what part of the body the structures are located in – e.g. the anatomy of the bones, blood vessels and nerves, etc. of the upper extremity is described in one place). All editions of "Gray's