biology

Furcula

Furcula is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Furcula rather than just read about it. In short: 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 either an interclavicle or formed by the fusion of the two clavicles. In birds, its primary function is in strengthening the thoracic skeleton to withstand the rigors of flight.

Key takeaways

Furcula belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Furcula to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Furcula from memory before moving on to harder problems.

Reference excerpt

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 either an interclavicle or formed by the fusion of the two clavicles. In birds, its primary function is in strengthening 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 scapulae. In conjunction with the coracoid and the scapula, it forms a unique structure called the triosseal canal, which houses a strong tendon that connects the supracoracoideus muscles to the humerus. This system is responsible for lifting the wings during the recovery stroke. 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. 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 stores 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. 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. In birds, the furcula also may aid in respiration by helping to pump air through the air sacs.

In other animals Several groups of theropod dinosaurs have also been found with furculae, including dromaeosaurids, oviraptorids, tyrannosaurids, troodontids, spinosaurids, coelophysids, and allosauroids. Seeing the occurrence in diplodocid dinosaurs of interclavicles, Tschopp and Mateus (2013) proposed that the furcula is a transformed and divided interclavicle, rather than a fused clavicle.

In folklore

Superstitions surrounding divination by means of a goose's wishbone go back to at least the late medieval period. Johannes Hartlieb in 1455 recorded the divination of weather by means of a goose's wishbone: "When the goose has been eaten on St. Martin's Day or Night, the oldest and most sagacious keeps the breast-bone and allowing it to dry until the morning examines it all around, in front, behind and in the middle. Thereby they divine whether the winter will be severe or mild, dry or wet, and are so confident in their prediction that they will wager their goods and chattels on its accuracy." Hartlieb wrote of a military officer: "This valiant man, this Christian Captain drew forth out of his doublet that heretical object of superstition, the goose-bone, and showed me that after Candlemas an exceeding severe frost should occur, and could not fail." According to the officer, "The Teutonic knights in Prussia waged all their wars by the goose-bone; and as the goose-bone predicted so did they order their two campaigns, one in summer and one in winter." 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. In some family traditions, the one receiving the smaller part made the wish. At that time, the name of the bone was merrythought. The name wishbone in reference to this custom is recorded from 1860.

See also Bird anatomy – Physiological structure of birds' bodies

Footnotes

References

Illustrations

Worked examples

Example 1 — a first encounter with Furcula

Start with the simplest possible case. Write down what Furcula claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Furcula before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Furcula ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Furcula

In research: Furcula appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Furcula in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Furcula is common in secondary-school and first-year university syllabi. It links to neighbouring topics Bird anatomy, Dinosaur anatomy, so understanding it makes those chapters shorter.
In everyday life: Look for Furcula outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Furcula in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Furcula means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Furcula out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Furcula in simple terms?

Why does Furcula matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Furcula?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Furcula.