Fig. 4. Injuring force mechanisms and resulting lesions. In  A , a compression hyperextension force has resulted in distraction of the elements of the anterior column and compression of posterior column elements; an avulsion fracture from the anterior-inferior margin of the vertebral body (  small arrow 2 ) and a fracture of the articular process (  small arrow 1 ) have resulted. In  B , a flexion (  large arrow 2 ), compression (  large arrow 1 ) force has produced a wedge fracture of the vertebral body (  small arrow 2 ) and an incomplete disruption of the interspinous and supraspinous ligaments (  small arrow 1 ).