Keel (bird anatomy) 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 bird's wing muscles attach, thereby providing adequate leverage for flight. Keels do not exist on all birds; in particular, some flightless birds lack a keel structure. Historically, the presence or absence of a pronounced keel structure was used as a broad classification of birds into two orders: Carinatae (from "carina", "keel"), having a pronounced
The Anatomy of Melancholy melancholia (which includes, although it is not limited to, what is now termed clinical depression). Although presented as a medical text, "The Anatomy of Melancholy" is as much a "sui generis" work of literature as it is a scientific or philosophical text, and Burton addresses far more than his stated subject. In fact, the "Anatomy" uses melancholy as the lens through which all human emotion and thought may be scrutinized, and virtually the entire contents of a 17th-century library are marshalled into service of this goal. It is encyclopedic in its range and reference. In his satirical preface to the