Biomechanics of the osseous bridge formation in the atlas vertebra as a consequence of the intentional cranial deformation

Abstract

Abstract From more than 5,000 years ago until the Conquest, practices aimed to cause permanent cranial deformities in individuals were common in pre-Columbian societies. Its purpose was to produce signs of identity of different types: religious, magical, aesthetic, ethnic or social. These modifications were made with boards, fabrics, and elastic straps that applied pressure to the newborn's head. There are many morphological variants, but a classification into four groups is generally accepted: Straight Circular, Oblique Circular, Straight Tabular and Oblique Tabular. In the anthropological investigation of bone samples from the archaeological site of the Huallamarca pyramid (Lima, Peru), the classification process collected a significant sample with oblique tabular deformation, which show a variant of simultaneous deformation in both the skull and the bone. from the atlas. In this first cervical vertebra the so-called Ponticulus Posticus is shown, a bony bridge resulting from bone remodeling, in which one of the theories about its origin is its generation due to the alteration of natural loads of the neck joint. The purpose of this article is the development and application of biomechanical techniques to verify this point of view, focusing the study on the one hand on the correlation between possible changes in the location of the center of gravity of the skull and, on the other, the consequent changes of loads on the atlas as a result of the intentional shape change of the skull.