The objective of this retrospective study was to delineate critical regions of trauma to the human cervical spine and determine the mechanisms of injury from motor vehicle accidents. Medical records and radiographs of adult patients admitted to the teaching hospitals of the Medical College of Wisconsin with the diagnosis of cervical spine fracture, and/or cervical spinal cord injury were reviewed. Based on the degree of spinal cord injury, the patients were divided into the following three groups: complete quadriplegia, incomplete quadriplegia, and no neurologic deficit. The retrospective evaluation identified flexion-compression, axial loading, extension, flexion-distraction, and flexion-rotation injuries among the three groups. Results indicated that the lower cervical spine is the most commonly injured region. Further, flexion-compression and axial loading of the head-neck complex were the most frequent mechanisms of injury in the complete and incomplete quadriplegic groups. In contrast, flexion-rotation injuries were also significant among patients with no neurologic deficit.