Fig. 3From: Free-hand technique of C7 pedicle screw insertion using a simply defined entry point without fluoroscopic guidance for cervical spondylotic myelopathy patients with C3 to C6 instrumented by lateral mass screws: a retrospective cohort studyIllustration of trajectory B. Ep B was located at the midpoint of the base of C7 superior facet. ɑ: transverse angle; β: sagittal angle; l: screw length; m: sagittal height; n: screw widthBack to article page