Variations of the human hyoid bone and its clinical implications

The aim was to determine the variations in shape of the human hyoid bone in terms of symmetry, isometry and anisomorphism. These parameters are useful for surgeons and/or forensic anthropologists. Sixty-two human hyoid bones (31 male and 31 female) belonging to the Instituto Anatómico Forense (I.A.F.) of Madrid (Spain) were dissected. The data collected were analysed using the chi-square test. The specimens were classified into five different patterns: U-shaped (16.7%), open (47.6%), triangular (9.5%), horseshoe-shaped (7.1%) and trapezoidal (19%). Types were distinguished according to the different shapes of the two halves (isomorphic 67.7% and anisomorphic 32.3%), the length of the greater horn (isometric 37% and anisometric 63%), and the transverse distances between the horns (symmetry 24.2% and asymmetry 75.8%). A thorough understanding of these anatomical variations could be useful for clinicians and forensics in interpreting the morphology of the hyoid bone.