Age-related morphological changes in squamous and parietomastoid sutures of human cranium

Age-related morphological changes in the inner and outer surfaces of the squamous and parietomastoid sutures were examined in 65 skulls (35 male, 30 female) obtained from Japanese subjects 5-90 years of age at the time of death. Dimensions were measured in both the horizontal and sagittal planes. Wavelength analysis was done by three-dimensional construction. Irregularities were evaluated by calculating fractal dimensions. The outer squamous suture showed no significant age-related changes in size, but wavelength increased because of the development of bony interdigitations with aging. The posterior part of the outer squamous suture showed significant age-related increases in both wavelength (p < 0.01, R(2) = 0.164) and fractal dimension (p < 0.01, R(2) = 0.101) in males. The parietomastoid suture showed significant age-related changes in size (p < 0.05), but not in wavelength or fractal dimension. These distinct morphological changes found on both the inner and outer surfaces of the squamous and parietomastoid sutures suggest that the age-related morphological characteristics of these sutures are affected by extrinsic mechanical forces.