forcing the vertebral bodies apart anteriorly subluxation) (Fig. 8.2). Hyperextension of an osteoarthritic cervical spine, in which the spinal canal is already narrowed by osteophytes, may lead to damage to the spinal cord through impingement upon it of infolded pieces of the tough ligamentum flavum or the osteophytes themselves(Fig. 8.13B); this results in the so-called'central cord syndrome, with characteristic incomplete loss of neurological function. Vertical compression acting through the skull may cause a fracture of the ring of the atlas(see Fig. 8.11) or a burst fracture of a vertebral body(Fig.83)