Two factors critical in the pressure response of the impacted head.

The response of the head to blunt impact in the posterior-to-anterior direction (+Gx) was investigated using anesthetized Macques (Macaca mulatta). Three-dimensional motion and epidural pressures were measured. The data were analyzed in the time domain using time histories and auto- cross-correlation functions; in the frequency domain, transfer functions were used. The results of the tests demonstrate that: 1) the thermodynamic response (fluid vaporization) of the cerebrospinal system is an important consideration when the impact produces significant tension, and 2) the interaction of the neck and the skull affects both the stresses produced in the brain and the injury response. These results are important for both the mathematical modeling of head trauma and establishing the injury tolerance of the head.