Furcula
The furcula (Latin for "little fork"; pl.: furculae) or wishbone is a forked bone found in most birds and some species of non-avian dinosaurs, and is formed by the fusion of the two clavicles.[1] In birds, its primary function is in the strengthening of the thoracic skeleton to withstand the rigors of flight.
In birds
The furcula works as a strut between a bird's shoulders, and articulates to each of the bird's
As the thorax is compressed by the flight muscles during downstroke, the upper ends of the furcula spread apart, expanding by as much as 50% of its resting width, and then contracts.[1] X-ray films of starlings in flight have shown that in addition to strengthening the thorax, the furcula acts like a spring in the pectoral girdle during flight. It expands when the wings are pulled downward and snaps back as they are raised. In this action, the furcula is able to store some of the energy generated by contraction in the breast muscles, expanding the shoulders laterally, and then releasing the energy during upstroke as the furcula snaps back to the normal position. This, in turn, draws the shoulders toward the midline of the body.[2] While the starling has a moderately large and strong furcula for a bird of its size, there are many species where the furcula is completely absent, for instance scrubbirds, some toucans and New World barbets, some owls, some parrots, turacos, and mesites. These birds are still fully capable of flying. They also have close relatives where the furcula is vestigial, reduced to a thin strap of ossified ligament, seemingly purposeless. Other species have evolved the furcula in the opposite direction, so that it has increased in size and become too stiff or massive to act as a spring. In strong flyers like cranes and falcons, the arms of the furcula are large, hollow and quite rigid.[3]
In birds, the furcula also may aid in respiration by helping to pump air through the air sacs.[1]
In other animals
Several groups of
Seeing the occurrence in
In folklore
The custom of two persons pulling on the bone with the one receiving the larger part making a wish developed in the early 17th century. At that time, the name of the bone was a merrythought. The name wishbone in reference to this custom is recorded from 1860.[9]
See also
References
- ^ ISBN 978-0-7167-4983-7.
- ISBN 0-300-07619-3.
- ^ The Inner Bird: Anatomy and Evolution, by Gary W. Kaiser
- ^ ISBN 0-12-226810-5.
- ISBN 0-253-34539-1.
- .
- PMID 23190365.
- ^ Edward A. Armstrong, The Folklore of Birds (1970), cited after Davis, Marcia. "Wishbone myth has long history". Knoxville News Sentinel. Retrieved 27 September 2012.
- etymonline.com