Everyone knows that owls easily and naturally turning his head in all directions, like the head on their hinges. The amazing ability of these birds to turn his head 270 degrees for a long time caused confusion among scientists. Pass through the neck vessels that feed the brain. With such a turn of the head at least would have to shrink the carotid artery. And indeed, other animals and people, in principle, are not able to perform such a sharp turn.
Scientists have unraveled the mystery of the School of Medicine at Johns Hopkins University in the U.S.. They studied the structure of the cervical spine in the white owl, little owl virgin and colorful owl. It turned out that the Soviet vessels that lie at the base of the head, are quite different from the human structure: in the lower jaw bone ballonoobrazno they are expanding. At the same man with the removal of vessels from the heart gradually narrowed. Available owls extension serves as a reservoir for the blood that nourishes the brain in the case of reduction of blood supply to the "bottom".
In addition, the cervical vertebrae of birds, too, have adapted to such rotations. As you know, through the cervical vertebrae are important blood vessels that feed the brain. With such a strong turn of the head neck vertebrae could damage blood vessels. Unlike other birds, owls special openings in the cervical vertebrae through which these important artery is 10 times wider than the diameter of the vessel, allowing it to remain intact even in a strong shift of the vertebrae. On top of that vessels owls are included in the cervical vertebrae above - not at the level of the 14th, as usual, and the 12th vertebra, which gives them more freedom.
And that’s not all devices owls. These birds between the vertebral and carotid arteries have anastomoses compounds that improve blood circulation in the brain, if there is a problem with the movement of blood through the carotid artery, the disadvantage can be compensated through the vertebral vessels. All these adaptations owls protect the brain from oxygen deficiency and its consequences with a strong turn of the head.