The average length of massa lateralis atlantis was 17.3 mm, space between the two entry points of screws 24.1 mm, height of odontoid 14.5 mm, width of odontoid 9.1 mm, anteroposterior diameter of odontoid 10.6 mm and height of axis 22.7 mm.

• 寰椎侧块长度为 17.；3mm；两侧块螺钉进钉点间距为 2 4