The research, published in The Anatomical Record, reports for the first time the number and size of these microscopic channels, known as vascular microforamina, which connect the cranial bone with the intracranial space.

To conduct the study, the team used computed tomography on a sample of adult human crania. The results show marked interindividual variability: each cranium may contain from around 100 to 400 of these small channels, distributed across the inner surface of the cranial vault.

Most of these conduits are extremely small, with diameters below 0.5 mm. However, the larger channels, although fewer in number, contribute a comparable share of blood flow. These are mainly concentrated in specific regions of the skull, particularly in the posterior and central areas of the parietal bone, in association with major venous structures.