Dimensions and ossification of the normal anterior cranial fossa in children.

BACKGROUND AND PURPOSE: Interpretation of CT of the anterior skull base in children depends on knowledge of the pattern and chronology of ossification. The purpose of this study was to ascertain the age at which the anterior cranial fossa is fully ossified as assessed on CT examinations. MATERIALS AND METHODS: This was a retrospective review of 127 CT examinations of children ranging from 1 day to 16 years 7 months of age without known or suspected anterior cranial fossa abnormality. Measurements of the length and width of the anterior skull base and the presence and size of the most anterior unossified portion were determined by 2 investigators. RESULTS: At birth, the anterior skull base consists mainly of cartilage. There is a wide variation in ossification rates between individuals, but the anterior skull base was fully ossified at 3 years 10 months in all of our cases. CONCLUSIONS: In healthy individuals, the anterior skull base is fully ossified by 4 years of age.

A quantitative and descriptive approach to morphological variation of the endocranial base in modern humans.

The cranial base is one of the major foci of interest in functional craniology. The evolution and morphogenesis of this structure are still poorly known and rather controversial because of multifactorial influences and polyphasic stages. Endocranial dynamics are associated anteriorly with the upper facial structures, laterally with the mandibular system and midsagittally with brain development. In the present study, we investigated the endocranial morphology of modern humans using 3D landmark-based approaches, i.e. geometric morphometrics and Euclidean distance matrix analysis. The structure of endocranial variation is poorly integrated, with only weak reciprocal influences among the three fossae. Some major variations are associated with changes in the posterior fossa, with possible consequences on the anterior areas. These main patterns of integration are hypothesized to be influenced by the connective tensors of the dura layers. Static allometry and sex differences are largely related to the ontogenetic sequences, characterized by early maturation of the anterior fossa with respect to the middle and posterior regions (i.e., relatively shorter posterior part of the planum sphenoideum and vertical lengthening of the clivus in males). The relative independence between the endocranial fossae, as well as their structural connection through the meningeal tensors, must be carefully considered in studies on the evolutionary dynamics, since they lead to mosaic changes through phylogeny.