Skeletonderdelen van zeevogels (2): Schoudergordel

The shoulder girdle consists of 5 bones: two scapulas, two coracoids and the furcula; the latter being two fused calvicles. In most birds the bones are separate and interconnected by ligaments, with some exceptions. The coracoids are, in general, short in soaring and gliding birds but longer in birds with a flapping flight. In pelicans and frigatebirds the furculas are fused to the apex of the sternum, in the latter also the coracoids are fused to the furcula. In other Pelicianiiformes and the Diving Petrels the furcula and sternum are nearly fused. In flight the furcula shows a spring action which is not yet fully understood. Thr sacupula is merely an accessory bone to connect the schoulder girdle to the rib case, not very specialized and mostly sabre shaped. In penguins the scapula is broad. Where the three bones meet is an opening for the tendon of the minor pectoral muscle and acts as a trolley.