Postnatal changes of the clivus.

We studied the size of the clival region (length, widest and narrowest diameter, and distance between two jugular tuberculi) in 77 skull bases or occipital and sphenoid bones from skeletons aged 3-80 years. The comparison of the measurement points among the age groups (3-10, 11-25, 26-60, and 61-80 years) showed that the final length of the clivus was reached by 11 years of life in both men and women, and then remained constant throughout life. All other measurements did not differ among the age groups. Also, only the length of the clivus strongly correlated with age (Pearson's r = 0.336, P = 0.0028). It seems that the postnatal age up to 11 years of life is the crucial time of the development of the clivus, when the final adult width of the clivus is first reached, followed by the finalization of its growth in length.