Incomplete decapitation of a motorcyclist from hyperextension by inertia: a case report.

This is a rare case involving a motorcyclist. A 57 year old motorcycle rider wearing a full face type helmet, suffered incomplete decapitation. The autopsy findings revealed a wide lacerated wound accompanied by extension marks in the front neck, atlanto-occipital dislocation and complete transection of the brainstem. According to the police traffic report, the man's head was stationary at the moment of impact and the remainder of the body continued in a backward motion. We concluded that the inertia of the torso caused hyperextension of the neck and subsequent incomplete decapitation.