Abstract: Objective To provide the anatomic and radiographic data, verify the clinical application of trans-lamina screws and evaluate the efficacy of our radiographic methods. Methods The anatomic and radiographic measurements of C2 vertebra were conducted on cadavers and living subjects. A total of 96 human adult cadavers and 112 volunteers without upper cervical abnormality were studied in this project. The minimal height (H1), thickness (T), length (L1) of C2 lamina, height of the root of lamina (H2), distance from the entry point to the lateral rim of lamina (L2) and to the lateral rim of lateral mass (L3) were bilaterally measured using calipers. The spino-laminar angles (angle A) were also included. All measurements were taken at the thinnest part of the lamina in the axial and coronal planes. Results The data of males were significantly higher than that of females (EM>P /EM><0.05) except angle A. There was no significant difference in the values of bilateral lamina between group A and group B (EM>P/EM> >0.05).The thickness of the vertebral lamina was less than 6mm in 45% of the specimens. The length of the lamina in all specimens was less than 2.5cm, while only 5% of the specimens had a >3cm distance from the entry point to the rim of lamina. The length from the entry point to the lateral rim of lateral mass ranged from 2.5cm to 4.6cm，with the length longer than 4cm was seen in 4% specimens. BR>Conclusion The preoperative radiographic evaluation is very important to determine the suitable size of screws. The radiographic measurement method we used is simple, accurate and reliable for preoperative measu

Key words: Axis, Lamina, Anatomy, Radiography, Measurement, Human