Forensic significance of the polymorphism of hyoid bone shape

The reasons why some hyoids fracture in strangulation and others do not may relate to anatomic features of the hyoid bone. On this basis, we studied the dimensions and shape of hyoid bones (n = 100) originating from the Terry collection, National Museum of Natural History, Smithsonian Institution. The hyoid bones were extensively polymorphic in both dimensions studied, the span or breadth, and the length of the cornua. There was no linear relationship between the breadth and length dimensions of the bone. Based on qualitative assessment, hyoid bones could be classed as either hyperbolic (55%) or parabolic (45%) in shape. Hyperbolic hyoid bones could be distinguished from hyoid bones with a parabolic configuration on the basis of the metric data although there was considerable overlap in the dimensions of hyoid bones of both configurations. Female hyoid bones tended to be smaller in both dimensions than male hyoid bones. The metric parameters of fractured hyoid bones from 10 cases (8 female, 2 male) of strangulation were compared with the dimensions of hyoid bones in this study. The metric features of the fractured hyoid bones were attributable to the predominance of females in the group of fractured hyoid bones studied, an observation that is anticipated because the majority of strangulations involve female decedents. On this basis, we conclude that variables other than the shape and dimensions of the hyoid bone are more relevant in determining if hyoid fracture occurs during strangulation.