Human cerebral blood vessels are frequently damaged in head impact, such as occurs in falls, contact sports, or vehicular collisions, resulting in intracranial bleeding. As an integral part of the support structure for the brain, these vessels also play a key role in the load response of the cranial contents. An understanding of the mechanical behavior of these arteries and veins, as well as their limiting loads, is thus required for a proper understanding and modeling of traumatic brain injury—as well as providing substantial assistance in preventive measures and even diagnosis and treatment. It is believed that axial stretching is the dominant loading mode for the blood vessels, regardless of the nature of the insult.

A total of 43 arteries and 24 veins from the cortical surface of the temporal lobe of the cerebrum were harvested from healthy patients in surgery and from cadavers in autopsy and successfully tested for mechanical properties. Most of the vessels were stretched to failure in the longitudinal direction, some quasi-statically and some dynamically, while a few arteries were inflated to failure. The significance of specimen and experiment parameters was determined through multivariate analysis of variance (MANOVA) testing. Longitudinal test results demonstrate that the arteries were considerably stiffer than the veins, carrying approximately twice as much stress as the veins at failure but withstanding only half as much stretch. Autopsy specimens were found to carry substantially less stress at failure than surgical samples, and no significant rate dependence was measured over a strain rate range of three orders of magnitude. Differences between tests resulting in failure at the grip and those rupturing in midsection were not found to be significant, and the extent of preconditioning was shown to be influential in measurements on arteries. Inflation tests on arteries demonstrated, as expected, that at a chosen circumferential stretch, circumferential stresses increase with more extensive axial stretches. Cortical arteries appear to be stiffer and stronger in the longitudinal direction than they are circumferentially. With regard to modeling, uniaxial vessel behavior over a limited span can be accurately represented by an exponential function, but a popular, two-dimensional constitutive model is shown to have major shortcomings in simulating combined inflation and stretch of the cortical arteries.