The mechanism of skull fracture.

Deformation patterns of the skull due to blows of low velocity, as well as the mechanism of production of linear skull fracture, have been previously described (1–5). When the dry skull is coated inside and out with “stresscoat” brittle lacquer, and then subjected to a blow, the lacquer cracks in the areas of greatest tensile deformation. The cracks appear on the outside of the skull in the regions in which the bone bends outward and on the internal surface where the bone bends inward. A region of inbending—generally circular, oval, or star-shaped—always surrounds the point of application of a blow, no matter where it is struck. Where the skull curves sharply, however, the extent of the inbending is not so great as in a less curved region. By means of the “stresscoat” technic, it has been shown that outbending of bone may occur at a considerable distance from the point of application of the blow. In some specimens a contrecoup type of outbending has been observed approximately diagonally opposite the poin...