Morphological relationship between the cranial base and facial anomalies in humans: Challenges and future perspectives

The cranial base (CB) and facial skeleton, despite differing in function and origin, are developmentally related. However, the mechanisms underlying the structural connection remain poorly understood. This article reviews CB malformations in congenital facial anomalies to identify the morphological basis for the relationship between these regions. Various types of CB deformities were identified in each facial anomaly; however, even anomalies with similar facial features did not necessarily share the same CB deformity, indicating that the underlying mechanisms exhibit complex interactions. To elucidate the biological processes related to these morphological interactions, detailed craniofacial geometry should be analyzed while retaining as much quantitative shape information as possible. Geometric morphometrics (GM) is an effective method for craniofacial studies because it analyzes shapes using landmark coordinates to retain relative geometric information, and it can be applied to complex shapes, such as curvatures or processes. Therefore, the application of GM in previous craniofacial studies is also reviewed. Quantitative data on normal and abnormal craniofacial development, encompassing both the prenatal and postnatal periods from GM studies, may provide valuable insight into the pathogenesis of congenital craniofacial anomalies.