By Jonathan AmosScience correspondent, BBC News

An owl demonstrates an 270-degree turn (Video by JHU)

It’s the owl’s greatest trick – turning its head almost a full circle.

The puzzle has been how the bird doesn’t throttle itself in the process. If we did it, we’d cut the blood supply to our brains and pass out.

But according to two US-based scientists, the owl has some very smart bone and vascular structures running along its neck to the skull.

These features protect blood vessels from damage and maintain the flow even when the head is swivelled 270 degrees.

“They haven’t developed just one answer to the problem; they have several answers,” said Dr Philippe Gailloud from Johns Hopkins University School of Medicine.

“And it’s because of this set of solutions that we don’t see lots of owls lying on the forest floor having suffered strokes,” the interventional neuroradiologist told BBC News.

Most birds have extremely flexible necks, but the owls are the avian species that have perhaps garnered the greatest attention for their neck-twisting exploits.

They must turn their heads in this extraordinary way because of their eyes’ narrow field of view and relative immobility.

It’s true they have double the number of bones in their neck compared with us – 14 versus seven cervical vertebrae. But it’s really the way the animal manages the flow of oxygenated blood to its brain that underpins the impressive feat.

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Jonathan.Amos-INTERNET@bbc.co.uk and follow me on Twitter:@BBCAmos