The hyoid of woodpeckers loops over top of the skull to completely surround their skulls. The hyoid helps direct the stress of impact below and around the skull (and brain) and also acts like a 'safety belt', helping to keep the brain in place. It is the movement of the brain inside the skull during impact, more than the blow itself, that causes concussions. If the brain is held in place, injury risks are greatly reduced. As in the above figure, time after impact proceeds from upper left to lowe
