Fig. 2

A schematic representation of C1-2 rotational angle. (A) A midline bisecting the C1 vertebra. C1 assimilation is present. (B) A midline bisecting the C2 vertebra. The angle between them represents the C1-2 rotational angle
A schematic representation of C1-2 rotational angle. (A) A midline bisecting the C1 vertebra. C1 assimilation is present. (B) A midline bisecting the C2 vertebra. The angle between them represents the C1-2 rotational angle