Science Reveals How Owls Avoid Stroke While Rotating Heads

So until your chiropractor can explain  how your neck structure is similar to an owls don't get your neck adjusted. Or for a more graphic image,Regan MacNeil from the Exorcist. 
http://news.health.com/2013/01/31/science-reveals-how-owls-avoid-stroke-while-rotating-heads/
What a hoot: Scientists say they’ve discovered how owls can almost fully rotate their heads without damaging the blood vessels in their necks or cutting off the blood supply to their brains.
Owls have four major bone structure and blood vessel adaptations that prevent injury when they rotate their head. Humans lack these adaptations, which helps explain why people are more vulnerable to neck injuries, according to the Johns Hopkins researchers.
“Until now, brain imaging specialists like me who deal with human injuries caused by trauma to arteries in the head and neck have always been puzzled as to why rapid, twisting head movements did not leave thousands of owls lying dead on the forest floor from stroke,” study senior investigator and interventional neuroradiologist Dr. Philippe Gailloud said in a Hopkins news release.

More at link.