Posts Tagged 'middle meningeal artery'

Craniovascular traits

The vascular imprints on the endocranial surface, the diploic channels within the vault bones, and the emissary foramina of the cranial cavity, are used to make inferences on blood flow in archaeological and paleontological samples. Unfortunately, basic information on many of these craniovascular traits (variation, distribution, homology, development, influential factors and even functions) is still poor for our own species. It sounds unpractical to investigate a feature in a few broken bones of an extinct species, if the same information is lacking for many billions living individuals. A former study was focused on the parietal bone. Now we have published a comprehensive endocranial survey on these traits in two modern European populations, to supply more information on their variability and on the influences of skull size and proportions, asymmetry, or sex. Blood flow exchange within the endocranial cavity may be relevant for thermal regulation and brain cooling. The final aim is to establish what functional or structural factors are involved in the morphology of these vessels and of their bony traces, as to interpret differences in extinct species or past populations. Many of these features bridge interests in anthropology and medicine.

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Little Foot

The endocast of the australopith StW 573 is pretty complete, and now Amélie Beaudet and colleagues have published a very detailed and comprehensive anatomical analysis of its features. For many paleoneurological traits we still miss a reliable knowledge on intra- and inter-specific variation but, according to what we can currently see in Australopithecus, Paranthropus and chimpanzees, StW 573 does not display derived sulcal patterns in the frontal and parietal regions. Its overall endocranial form resembles the morphology of some Paranthropus specimens, although in this case there are still some issues on deformation and possible taphonomic effects (specially at the frontal bone). The study supplies a careful description of the vascular patterns, in particular for the middle meningeal artery. In humans, only our species has generally a complex vascular network, while vessels are more scarce and less connected in extinct human taxa. Nonetheless, these same vessels (or, at least, their analogous networks) are more developed in apes. Therefore, australopiths are a key group to understand what happened with these traits, and to assess the polarity of these features in the evolution of distinct hominoid branches.

Bones and vessels

Eisova et al 2016The vascular traces left on the bones are remnants of physiological processes associated with blood flow and functions. Craniovascular traits can be used in archaeology, paleontology, and forensic science to deal with normal and pathological variations of the circulatory system, bridging interests between evolutionary and medical fields. Current information on these characters is, at best, scarce. After our recent work on diploic channels, this week we publish another morphometric study on the vascular traces, and specifically on their relationships with parietal bone size and thickness. We provide a quantitative description of the lumen size in adult modern humans for the middle meningeal and diploic vessels, as calculated from cranial anatomy after computed tomography, for different orders of branches. Vessel size and cranial thickness can be proportional if sharing growth factors, or inversely proportional if competing through structural constraints. However, we do not find any clear relationship between vascular size, cranial size, and cranial thickness. This result suggests that bone and vessel morphogenesis are probably influenced by independent factors, at least when dealing with differences among adult individuals.


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