Morphological Integration of the Orbital Region in a Human Ontogenetic Sample

Abstract

Most studies on craniofacial morphology have focused on adult individuals, but patterns of variation are the outcome of genetic and epigenetic variables that interact throughout ontogeny. Among cranial regions, the orbits exhibit morphological variation and occupy an intermediate position between neurocranial and facial structures. The main objective of this work was to analyze postnatal ontogenetic variation and covariation in the morphology of the orbital region in a cross-sectional series of humans from 0 to 31 years old. Landmarks and semilandmarks were digitized on the orbital rim, as well as in neighboring neural and facial structures. Data were analyzed using geometric morphometrics. Results indicated that orbital size increases during the first years of postnatal life, while the shape of the orbital aperture does not change significantly with age. In general, the pattern and magnitude of shape covariation do not vary markedly during postnatal life although some subtle shifts were documented. Additionally, the shape of the orbital aperture is more related to the anterior neurocranium than to zygomatic structures, even when the allometry is adjusted. Although we expected some influence from postnatal craniofacial growth and from some functional factors, such as mastication, on the development of the orbits, this assumption was not completely supported by our results. As a whole, our findings are in line with the prediction of an early influence of the eyes and extraocular tissues on orbital morphology, and could be interpreted in relation to processes promoting early neural development that coordinately affects orbital traits and the neurocranial skeleton. Anat Rec,

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

“…Finally, virtually all studies describing midfacial growth in infancy and early childhood concur in the conclusion that the first year of life is the period of the most rapid postnatal growth with circum‐orbital dimensions showing the highest rates of change (Barbeito‐Andres et al, ; Humphrey, ; Waitzman, ). Another common finding is that the vertical dimensions of the face and nose (e.g., upper facial height) lag behind the transverse measurements (e.g., bizygomatic breadth) during the first years of life (Buschang et al, ; Farkas et al, ; Vidarsdottir et al, ).…”

“…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, ).…”

“…Existing approaches to this problem are numerous (see Bastir, Rosas, & O'Higgins, ; Cardini & Elton, ; Esteve‐Altava, ). The “classical” view on modularity considers the skull to be a number of relatively independent and spatially integrated units, e.g., “orbital,” “nasal,” and “masticatory” (see Martínez‐Abadías et al, ; von Cramon‐Taubadel, for an extensive review of modularity in the human skull and Esteve‐Altava, for a review of zoological literature), each having its own growth trajectory and pattern of variation (Barbeito‐Andres et al, ; Bastir et al, ; Bulygina et al, ; Sardi et al, 2005; Wheat, ). It is noteworthy that the number of units and their boundaries varies substantially from study to study (Cardini & Elton, ; von Cramon‐Taubadel, ).…”

Ontogenia de las órbitas en Pan troglodytes: implicancias estructurales, funcionales y evolutivas

“…Estudios ontogénicos de Homo sapiens (Barbeito-Andrés, 2014; Sardi & Ramírez Rozzi, 2005) indican que la mayor parte de la morfología y el tamaño orbital se establece en los primeros años de vida y muestra cambios menores hasta la etapa adulta. Asimismo, y no obstante la cantidad de elementos que conforman la cavidad, sus rasgos están fuertemente integrados, en mayor medida con el neurocráneo anterior y más débilmente con la cara (Barbeito-Andrés et al, 2016). Sin embargo, poco se sabe sobre los cambios ontogénicos de la órbita de otros primates en cuanto a su posición relativa a otras estructuras y menos aún en cuanto a aquellos cambios que puedan afectar el campo visual.…”

Shape analysis of spatial relationships between orbito‐ocular and endocranial structures in modern humans and fossil hominids

“…However, recent research shows that following the first year of postnatal life, and as the various anatomical components comprising the orbit begin to ossify, no significant change is observable in size or shape of the orbital aperture (Barbeito‐Andrés et al. ). In fact, during later stages of postnatal development, when the eye continues to grow rapidly but after the orbit has already ossified, the effects of added ocular growth on orbital size are negligible (Washburn & Detwiler, ; Hoyte, ).…”