Verification of the child crash test dummy neck response using magnetic resonance imaging and physiologic muscle stress

The purpose of this work is to verify and modify, if necessary, the neck response characteristics of the current child crash test dummies using magnetic resonance imaging and muscle physiology. The child crash test dummy neck response is scaled from the responses of adult necks using the neck circumference ratio (child to adult) as a means for adjustment. This method of scaling relies heavily on external body anthropometry and contains certain assumptions about the internal anatomies and muscle physiology. The response scaling laws employed are derived from geometric and dynamic similitude and are a widely accepted method for modeling system behavior using a scale model. However, the model is required to possess geometric similarity and homogeneity. In the case of the child neck, it is plausible that certain anatomies do not scale according to the external body dimensions. Even though the neck volume may scale nicely with the neck circumference, the distribution of the bony anatomies and musculature may scale quite differently.; The child neck response scaling relies on neck circumference, which is easy to measure and linear in the characteristic dimensions (neck depth and breadth). This scaling was conducted before the wide availability of whole body scanning techniques. Therefore, the relevant internal anatomies have never been evaluated for consistency with the anthropometric neck response scaling.; An integral part of the neck response scaling includes an assumption regarding the physiologic potential of the muscle tissues themselves. The ability of the muscle to produce force for a given cross-section (physiologic muscle stress) is considered not to vary with age. The study will address this issue as well. In all three key areas are investigated: (1) Scalability of the neck musculature; (2) Scalability of the neck muscle attachments; (3) Physiologic muscle stress variations with age.; These three areas will be assessed using methods that rely on magnetic resonance imaging for accurate measurements of internal body anatomies. Volunteers range in age from neonate to sixty-four years of age.