Craniovascular morphology

Eisova et al 2016Studying anatomical variability in paleontological and archaeological context is a challenge to look behind (and beyond) the bones. In the case of cranial remains we are able to make inferences not only on bone morphology but also on part of the vascular system. With computed tomography we can observe the diploic channels inside the bone matrix, and the imprints of the middle meningeal vessels on the endocranial surface of the vault. In the parietal bone both networks are particularly developed, most of all in modern humans. This month we have published a new study focusing the size and morphology of these vascular imprints in adult humans, and on their relationship with bone size and thickness. Our aim was to reveal possible influences between vascular and bone morphology. Vessels and bones share morphogenetic processes, and there can be shared functional and structural relationships between angiogenesis and osteogenesis. Shared growth factors can generate a positive correlation between bones and vessels dimensions or, conversely, biomechanical constraints between bone matrix and its embedded soft tissues can generate an inverse relationship between their volumes. We used CT data of human adult crania to measure cranial size, parietal bone thickness, and lumen size of these vascular traces. We provide a metric description of the size variation and size distribution of the diploic channels and meningeal imprints, for different orders of branches. The diploe largely influences the overall thickness of the bone. The upper part of the parietal bone shows the thickest values. The lumen size of the diploic channels and meningeal imprints is very similar, with no patent sexual or hemispheric differences. The correlation analysis did not revealed any clear relationship between vessels size, cranial size, and cranial thickness. Therefore, these results do not support the hypothesis of a reciprocal influence between bone and vascular morphology, which are likely to respond to different factors. Actually, although some vascular changes may be described in extreme cases of cranial deformation, also according to a previous survey on the endocranial vascular pattern in normal variation there is no apparent correspondence between gross cranial form and craniovascular traces.

Stáňa Eisová

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