Functional Morphology of the Basicranium

Abstract

Shells of the dimensions of a hominoid skull base, loaded by forces equivalent to the weight force, joint forces, and muscle forces acting on the neurocranium, are subjected to stress due to bending. As large areas of the wall contribute to the absorption of the external forces, shell structures possess considerable load-bearing capacities. Unlike many shell structures used in architecture, the walls do not act as membranes. Membranes are characterized by the absence of bending stresses, and are thus the most economical shell structures. Examples of membranes found in nature are egg shells and all hydraulic systems (Bonik et al. 1978). The membrane principle may well be found in the early embryonic developmental stages of the skull; such a structure does not, however, provide the resistance necessary to withstand punctual forces acting normal to the wall, such as joint forces or impact loadings.