Vascular microforamina and endocranial surface: normal variation and distribution in adult humans

Abstract

The term craniovascular traits refers to the imprints left by arteries and veins on the skull bones. These features can be used in anthropology and archaeology to investigate the morphology of the vascular network in extinct species and past populations. Generally, the term refers to macrovascular features of the endocranial cavity, like those associated with the middle meningeal artery, venous sinuses, emissary foramina, and diploic channels. However, small vascular passages (here called microforamina or microchannels) have been occasionally described on the endocranial surface. In this study, we describe and quantify the amount and distribution of these microforamina in adult humans (N = 45) and, preliminarily, in early to late juvenile subjects (N = 7). Adults display more microchannels than juvenile skulls. Females show more channels than males, and it should be evaluated whether this trait can represent a new described sexual features, influenced by sex biology. The distribution of the microforamina is particularly concentrated on the top of the vault, in particular along the sides of the sagittal, metopic, and coronal sutures, matching the course of major venous sinuses. Nonetheless, the density is lower in the region behind the bregma. A preferential pattern of distribution seems to join diagonally the coronal and dorsal parietal regions. Beyond oxygenation, these features are likely involved in endocranial thermal regulation and immune responses, and their distribution and prevalence can hence be of interest in human biology, evolutionary anthropology, and medicine.