The growth rate of the human cranial base between nasion and inion.

The growth rate of the human cranial base between nasion (N) - tuberculum sellae (Ts) and tuberculum sellae - internal occipital protuberance (= Twining's line (Tw)) were calculated in proportion to nasion - inion (N - I) distance and expressed in two cranial base ratios: (see formulas) The growth rate of the whole cranial base showed a notable stability and a given ratio apparently prevails through into later life.