Raw Data, PC scores, and secondary variables

The skull base serves as structural support for the brain and an important conduit for cranial nerves and vessels. Paraclival and parasellar features are particularly complex, as these sites represent the union of multiple bony elements with many neurovascular components. Although morphometric descriptions of these components are common, these methods have intrinsic limitations which make global assessment of these anatomical features and their relationships very challenging. Here we apply geometric morphometric (GM) techniques to address the problems associated with traditional morphometric strategies of evaluating skeletal and soft tissue components of the skull base. Our aims are to describe the geometry of relevant skull base features and assess the relationship between 3-D shape variables and more traditional craniometric variables. A Microscribe® i+ 3-D digitizer was used to register the location of 20 3-D skeletal and neural landmarks on the skull base of the middle and posterior cranial fossae on 80 anatomical body donors (mean age 83.0 ± 10.1 years). Linear measurements of neurocranial length, width, skull base length, and ulnar length (as a proxy for general body size) were collected with traditional methods. A principal component analysis (PCA) was applied to Procrustes aligned coordinates. The results of the PCA revealed 27 principal components (PCs). The first component accounted for 34.24% of the variation in the sample and was associated with changes in clival width with corresponding changes in sella turcica length. Shape changes associated with PC1 scores correlated with configuration size (centroid size) (R2=.532, p