C1-C2 transarticular screw fixation (Magerl and Seemann). A, Landmarks for entry point of transarticular screw. B, Wires are brought around arch of C1 and spinous process of C2 to manipulate these two vertebrae. Screw holes are drilled through isthmus near its posterior and medial surface of C2 and outer lateral mass of atlas. C, Measuring screw length and tapping with 3.5-mm cortical tap. D, Proper screw placement for C1-C2 fusion. SEETECHNIQUE 41.11.