The differential roles of periosteal and capsular functional matrices in orofacial growth

Historically students of craniology believed, erroneously, that only the active processes of surface deposition and resorption and of interstitial expansion were involved in skull growth. The introduction of the method of functional cranial analysis placed primary emphasis on the morphogenetic role of the functional matrix. The two principal types of functional matrices, the periosteal and the capsular, are defined. The former alter the size and shape of the skeletal tissues while the latter alter spatial position. The majority of facial skeletal growth is shown to be due to the passive translation of the skeletal tissues within the orofacial capsule, responding to the prior and primary volumetric expansion of the oro-nasopharyngeal functioning spaces, acting as capsular matrices.