A systematic approach to the interpretation of gunshot wound trauma to the cranium

This chapter employs the fracture assessment triad, a systematic analytical approach, as a vehicle to explore the components used to interpret gunshot trauma to the cranium. First, a list of pertinent observations associated with gunshot trauma to the cranium is presented with a brief description of each. These features include entrance and exit wound defect morphology, keyhole defect, gutter defect, radiating fractures, concentric fractures, bone plugs, and associated foreign material, debris and residue. Second, the intrinsic factors that govern the way bone responds to trauma can be surmised through a direct examination or knowledge of the skeletal case. Intrinsic factors rest primarily in bone being a viscoelastic material with anisotropic properties, but include other elements that affect fracture production, such as buttressing, bone architecture, sutures, and influences of age, sex and health. These influences may be discoverable and factored into the analysis. With direct observation of the defect/fracture pattern and an understanding of the intrinsic influences involved, the extrinsic factors can be deduced. Bullet velocity, mass, design and cavitation represent the major extrinsic factors involved in wound production. The interplay of each of these factors imparts varying amounts of kinetic energy to soft and hard tissues. The greater amount of kinetic energy conveyed, the larger the temporary cavity and the greater the potential for destruction. When interpreting gunshot trauma, precision is enhanced by the analyst's familiarity with firearms and ammunition, facilitating determination of firearm type (rifle/handgun or shotgun), bullet direction, range, sequence of fire, and potentially, speculations as to bullet velocity, mass and design. Neither caliber nor gauge can be determined from the entrance defect size, but elimination of certain calibers or gauges may be possible.