The screw should be placed at the cross point which is 20 mm beside the midpoint of atlantal posterior tubercle and 3 mm above the inferior margin of arcus posterior atlantis during the operation of atlantal lateral mass screw-plate internal fixation.

• 寰椎侧块螺钉的进钉点选在寰椎后结节中点旁20 mm与后弓下缘以上3 mm的交点处,与矢状面保持(8~14)°。