Résumé
Research on the skull base is important to improve our understanding of the growth and development of the modern human skull. To study the growth of the human fetal skull base, we assessed a new geometric morphometric tool, which does not require the use of bone landmarks.
Seven dry fetal skulls of an estimated gestational age ranging from 15 to 27 weeks were studied. Each skull was scanned using a standard CT scan and the image sets were post-processed to extract volumetric data by segmenting the skull base into predefined regions of interest. Our method of analysis was based on the inertial properties of reconstructed volumes.
The volumetric study of the skulls highlighted an asynchronous speed of growth between the pre and post-chordal parts of the skull base whose preferential growth are in the vertical and horizontal planes. We also found different speeds of growth in the pre-chordal part depending on the type of ossification (endochondral or membranous). The overall shape of the skull base bones were preserved during the period studied except for the petrous pyramids. The expansion of bone parts was isometric with reference to a central point that was located at the intrasphenoidal synchondrosis. Finally, the analysis of the basicranial angles corroborated data from the literature in the sagittal plane and allowed their study also in the frontal and horizontal planes.
This three-dimensional volumetric approach is a necessary complement to studies that are performed in the sagittal plane and are based on the identification of landmarks. The geometric morphometric method used by authors permitted to obtain original informations on the growth kinetics and bone tridimensional movements of the human fetal skull base.