Brief synopsis of cranial sutures: Optimization by adaptation

This article reviews the form and function of cranial sutures across the temporal and spatial scales. The temporal scale spans 530 million years, from ostracoderms to contemporary humans. The spatial scale spans eight orders of magnitude, from the macroarchitectural level (the entire cranium), through the mesoarchitectural (the local/regional bone-suture-bone complex) and microarchitectural levels (tissues and cells), to the nanoarchitectural level (molecules within and outside the cells). A mechanomorphologic loop, or cycle, exists. The mechanical strain experienced by the sutures eventually alters the morphology of the sutures. In turn, these morphological changes affect the strain distribution within and around the sutures. At the microarchitectural level, the responses of bone and sutural cells to environmental perturbations depend on the content (what that perturbation is), the context (the other coexisting extrinsic and intrinsic factors), and the history of the perturbation (how often and for how long).