Modifications of the skull base in artificial deformations of the circumference of the head.

Four artificial deformations of the skull (collection of the Laboratoire d'Anthropologie of the Musée de l'Homme) have been analysed in terms of their morphology and osteometry. The study of the endocranial base in the three planes of space was made possible by a computerised three-dimensional reconstruction based on data gathered by CT. These four skulls were paired as regards their shape (2 annular and dolichocephalic and 2 tabular and brachycephalic) and as regards their age (2 skulls of children and 2 of adults). Certain modifications of the base, such as a tendency to platybasia and to an antero-superior tilt of the posterior fossa around an axis passing through the basion, could be observed in the two modalities of deformation studied. The existence of a region little subject to modelling combining the body of the sphenoid and the basilar and lateral portions of the occiput was confirmed as regards the chondrocranium, whereas the peripheral structures of the base were remodelled like the membranous structures of the vault of the neurocranium.