Ontogenetic Patterns of Morphological Variation in the Ectocranial Human Vault

Abstract

The skull is considered a modular structure in which different parts are influenced by different factors and, as a result, achieve adult shape at different ages. Previous studies have suggested that the basicranium presents a modular pattern that distinguishes sagittal and lateral parts, probably affected by the brain and masticatory structures, respectively. The vault of modern humans, in contrast, has been considered as a highly integrated system mainly influenced by brain growth. Here, we explored developmental shape variation in sagittal and lateral ectocranial vault in humans in order to assess if both regions are ontogenetically dissociated. We used a sample of 135 cranial computed tomography images from 0 to 31 ages. Landmarks and semilandmarks were collected on sagittal and lateral regions and geometric morphometric techniques were applied separately for each region. On the shape coordinates, we used Goodall's Ftest in order to assess the age when the adult configuration is attained. Principal component analysis enabled us to evaluate shape variation during ontogeny. Results indicated that both sagittal and lateral structures attain adult shape at early adolescence. Both regions express coordinated shape modifications probably due to shared developmental factors. It is concluded that masticatory muscles may not exert a strong enough influence to produce independent variation in the lateral traits. Thus, it is likely that the brain integrates sagittal and lateral parts of the vault across human ontogeny.

Midfacial growth patterns in males from newborn to 5 years old based on computed tomography

“…Some authors define an arbitrary threshold for each specimen which allows an apparently better visualization of bone tissue (Bastir & Rosas, ; Delye et al, ; Park, Yu, Kim, Lee, & Baik, ; Heuzé et al, ; Kim et al, ; Stull et al, ; Titiz, Laubinger, Keller, Hertrich, & Hirschfelder, ). Others define one standard threshold for all specimens which can then be manually adjusted to better visualize the anatomy of a particular individual (Anzelmo, Barbeito‐Andres, Ventrice, Pucciarelli, & Sardi, ; Barbeito‐Andrés et al, 2012; Barbeito‐Andres, Anzelmo, Ventrice, Pucciarelli, & Sardi, ; Cavalcanti et al, ; Chen, Por, Liou, & Chang, ; Decker, ; Hassan et al, ; Hwang et al, ; Kragskov et al, ; Morimoto, Ogihara, Katayama, & Shiota, ; Van Cauter et al, ; Young et al, ).…”

Developmental covariation of human vault and base throughout postnatal ontogeny

“…3 and 4). Some studies described similar trends of morphological changes considering the sagittal profile (Bookstein et al, 2003;Anzelmo et al, 2013) while in the present work, lateral variation in the vault and the base was also evaluated. Here, it was shown that infant globular vaults are characterized not only by shorter and higher configurations but also by marked laterally expanded frontoparietal regions (Figs.…”

Integración ontogenética en la morfología craneofacial humana

“…En HSAM estos músculos son relativamente débiles, lo que se evidencia en la ausencia de superestructuras óseas prominentes para la inserción muscular, tal como se observa en otros primates (Moss y Young, 1960;Aiello y Dean, 2002). Por esto, se acepta que el encéfalo es el principal modelador de la forma y el tamaño del neurocráneo y más particularmente del endocráneo (Moss y Young, 1960;Anzelmo et al, 2013). La base se ve adicionalmente afectada por los cambios que ocurren en la región facial y la columna vertebral (Lieberman, et al, 2000a, b).…”

“…Tanto en la bóveda como en la base, el modelo que separa los rasgos laterales de los mediales no encontró sustento suficiente en los resultados. Esto coincide con lo descripto por Anzelmo et al (2013) quienes hallaron que los rasgos sagitales y laterales de la bóveda completan su maduración coordinadamente, lo cual es una evidencia de integración entre ambas. La discrepancia con otros estudios en los que se sostienen estos módulos (Bastir y Rosas, 2005) podría ser atribuida a las diferencias respecto de los puntos morfométricos relevados, además de que Bastir y Rosas (2005 relevaron puntos en radiografías laterales, un soporte diferente al empleado en esta tesis.…”