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A computational head-neck model was developed to more efficiently study dynamic responses of the head and neck to near-vertex head impact. The model consisted of rigid vertebrae interconnected by assemblies of nonlinear springs and dashpots, and a finite element shell model of the skull. Quasi-static flexion-extension characteristics of ten human cadaveric cervical spines were measured using a test frame capable of applying pure moments. The cadaveric motion segments demonstrated a nonlinear stiffening response without a no-load neutral zone. Computational model parameters were based upon these measurements and existing data reported in the literature. Geometric and inertial characteristics were derived from three-dimensional reconstructions of skull and vertebral CT images. The model reproduced the shape and timing of the cervical spine buckling deformations observed in high speed video of cadaveric studies of near-vertex head impact [1].

This study explores the dynamics of head and cervical spine impact with the specific goals of determining the effects of head inertia and impact surface on injury risk. Head impact experiments were performed using unembalmed head and neck specimens from 22 cadavers. These included impacts onto compliant and a rigid surfaces with the surface oriented to produce both flexion and extension attitudes. Tests were conducted using a drop track system to produce impact velocities on the order of 3.2 m/s. Multiaxis transduction recorded the head impact forces, head accelerations, and the reactions at T1. The tests were also imaged at 1000 frames/sec. Injuries occurred 2 to 30 msec following head impact and prior to significant head motion. Head motions were not found to correlate with injury classification. Decoupling was observed between the head and T1, resulting in a lag in the force histories.