This exhibit features an enlarged detail of a brain cross section to highlight the layers of surrounding tissue in relation to a subarachnoid hematoma. Skin, subcutaneous fat, galea aponeurotica, and pericranium cover the outer skull. The skull interior is lined with endocranium and dura mater. The dura mater is a tough, membranous sac that protects the brain. It also contains cerebrospinal fluid and the venous sinuses. Beneath the dura lies the leptomeninges (arachnoid mater and pia mater), which cover the brain, and also contain cerebrospinal fluid. Cerebral arteries travel through the subdural spaces and supply blood to the brain tissues. Trauma to the head causes injury to the cerebral arteries, leading to the formation of a hematoma in the subarachnoid space. Swelling of brain tissues results in constriction of the vasculature, and ischemia of the surrounding brain.