C1 lateral screws and C2 pedicle/pars screws.

A variety of techniques exist for fixation of the upper cervical spine. The development of universal posterior cervical screw-rod instrumentation systems has resulted in recent interest in new and stable segmental fixation into C1 and C2. The C1 lateral mass is a safe and robust anchor point; however, the anatomic corridor to access the screw entry portal is unfamiliar. Understanding the C1 bony landmarks and the course and relationship of the soft-tissue structures (such as the vertebral artery and the C2 nerve root) is critically important. Alternative techniques for achieving segmental screw fixation into C2 are being developed. With polyaxial screw heads and lateral offset connectors, screw anchors can be driven into the most sturdy and safest aspects of C2 without concern for the position of the longitudinal rod.