Upper cervical trauma in motor vehicle collisions.

Motor vehicle collisions can cause a variety of injuries in pedestrians and vehicle occupants. Fatal and nonfatal trauma to the upper cervical spine, that is, atlanto-occipital junction, atlas and axis, can be part of this spectrum. Certain distinctive injuries (for example, "hangman's fracture") which occur result from the unique anatomic structure of this area and the various disruptive forces such as extension, distraction (tension), compression (axial loading), shear, and inertia generated during collision. Correlation of autopsy findings or radiological information of these cervical injuries or both with scene investigation can be informative not only in the determination of morbidity and mortality, but also in the assessment of injury mechanisms and improvements in occupant protection.