The cranial base in normal and abnormal skull growth.

In the normal growth of the cranial base, an outline of prenatal development stressed the common vertebrate plan, the patterning of mesenchymal tissues formed from and influenced by migrating neural crest cells. Details are given of the sequences of chondrification and ossification. Postnatal growth is approached in two ways--sagittal growth and transverse growth--involving detailed consideration of sutural growth and of resorptive expansion and remodeling in the whole base. New conclusions have been reached about the growth of the ethmoid, which continues for a longer time than was generally thought, and of its relation to orbital growth. The dependence of fossa growth upon the early, almost explosive growth of the brain is shown in the sequences of basicranial growth, with the maturation of the fossae in a rostrocaudal direction. Of all the suture systems affecting the base, the coronal ring is most important (with the spheno-occipital synchondrosis next in importance). An off-shoot of the coronal ring is noted, the pterygoid buttress, and its importance stressed in relation to maxillary and midface growth. These considerations of normal morphology are widened to explore the dysmorphologies of the nonsyndromic and syndromic craniosynostoses. The abnormal patterning of these synostoses is shown to lie partly in the common pathways of expressivity of the calvarial and basicranial suture systems, again particularly the coronal ring, and partly in the development and responsiveness of the bony units themselves, whether normal or hypoplastic, and of their soft-tissue matrices.