A posterior cervical fixation system includes a facet lock comprising an elongate member having distal and proximal ends. A tapered wedge projects axially from the distal end and defines a wedge axis, the wedge being sized and configured for insertion into a facet joint of a cervical spine. The facet lock includes opposing first and second dovetail recesses. The system further includes a tubular guide having distal and proximal ends and a lumen extending therethrough along a central axis. The tubular guide has a plurality of dovetail projections extending exteriorly outwardly, each dovetail projection terminating in an engagement surface that is spaced respectively at a different radial distance from the central axis. Each dovetail projection is configured for individual releasable attachment to one of the facet lock first or second dovetail recesses to selectively space the wedge axis and the central axis at different distances for lateral mass screw placement.