Mathematical modeling of the head and neck response to -Gx impact accelration (minimum articulation requirements).

Data on the dynamic response of the living human head and neck to -Gx impact acceleration was analyzed. The Calspan 3-D Computer Simulator of a Motor Vehicle Crash Victim was used to provide estimates of the head and neck response to be expected for the very specific deceleration profiles simulated. Two segments connected via a pivot were used to represent the head-neck system. The monitored T1 deceleration profile was used to drive this system and the simulation head-neck response was checked for accuracy in replicating motional characteristics and trends in the response mechanism. Two head pivot locations were considered. The first was the occipital condylar point and the second was a theorized hingepoint in the head which minimized the distance from this point to the T1 anatomical coordinate system over the range of body orientations observed in the photographic data. For the two geometrical representations, a successive approximation technique was employed to analyze the resulting data. This approach initially removed all constraints to head and neck motion, and the resulting simulation results were compared to the human data. Restrictions to head and neck motion were then successively added until an adequate replication of the human data was obtained. This approach made it possible to correlate specific events, such as loading of the head-to-neck dorsiflexion limiting angle, to head deceleration profile characteristics. Results were compared to calculations obtained for eight additional subjects and proved to be in good agreement.