Grytsyshina E E, Kuznetsov A N, Panyutina A A
Biological Faculty of the Moscow State University, Moscow, 119992, Russia.
Institute of ecology and evolution of the Russian Academy of Sciences, Moscow, 119071, Russia.
Dokl Biol Sci. 2016;466:24-7. doi: 10.1134/S0012496616010087. Epub 2016 Mar 30.
To analyze extreme sideways turn of the head in owls, a total fresh specimen of Strix aluco was frozen in respective posture and CT-scanned. The maximum turn to one side was found to be 360°, provided that the head is drawn into the shoulders. 160° of this full turn are ensured by the neck axial rotation (this includes ~90° twist of the head relative to epistropheus and, posterior to it, less than 15° per every cervical joint), and the rest 200° are ensured by combination of dorsal and lateral flexion. The 15° limit is overcome in five joints in respect of dorsiflexion, and in six joints in respect of lateral flexion. So large a degree of lateral mobility is unusual among birds, and is appreciated as a crucial adaptation to extreme head turning.
为了分析猫头鹰头部的极端侧向转动，将一只完整的长耳鸮新鲜标本以相应姿势冷冻并进行CT扫描。如果头部缩入肩部，发现向一侧的最大转动角度为360°。这一完整转动中的160°由颈部轴向旋转确保（这包括头部相对于枢椎扭转约90°，在枢椎后方，每个颈椎关节扭转小于15°），其余200°由背屈和侧屈的组合确保。背屈方面，有五个关节突破了15°的限制，侧屈方面，有六个关节突破了15°的限制。如此大程度的侧向移动性在鸟类中并不常见，被认为是对极端头部转动的关键适应。
