Spine & spinal cord: a free MRCS Part A question

This is a Jefferson burst fracture of the atlas from axial loading. The atlas is a ring with no body, so the load splits the ring at its weakest points and the lateral masses spread apart. The transverse ligament of the atlas runs between the tubercles on the medial aspects of the lateral masses and holds the dens against the anterior arch; combined lateral mass overhang of more than about 7 mm implies that it has ruptured, allowing anterior translation of the atlas on the axis and threatening the cord. The alar ligaments run from the dens to the occipital condyles and check rotation; the apical ligament is a small vestigial band from the tip of the dens to the basion; the tectorial membrane is the upward continuation of the posterior longitudinal ligament; the ligamentum nuchae is a posterior midline raphe of no stabilising importance here. Reference: Last's Anatomy 12e; Apley and Solomon's System of Orthopaedics and Trauma 10e.