Biomechanics of the Osseous Bridge Formation in the Atlas Vertebra as a Consequence of Intentional Cranial Deformation

Pre-Columbian societies carried out practices intended to cause permanent artificial cranial modification in individuals within their society to distinguish certain groups from others. These practices were carried out using boards, fabrics, and elastic straps to apply pressure to the newborn’s head to irreversibly alter it. Modifying the skull in this way is sometimes linked to a physical alteration of the atlas vertebra, the ponticulus posticus, based on ossification of the atlanto-occipital ligament and covering the passage of the artery. Over the years, there has been debate about its possible origin, ranging from a congenital cause, a pathological one, or the result of adaptation following a biomechanical change. The objective of this study is to verify this last origin in a sample from the pre-Hispanic Huallamarca pyramid in Lima, Peru, by locating the equilibrium point and determining whether there is a change in the center of gravity in deformed skulls and, consequently, whether this affects the pressure generated in the area where the ponticulus posticus appears.