Vascular anatomy: the head, neck, and skull base.

Knowledge of the anatomy of the vasculature of the head and neck from the thorax to the skull base is critical to the approach to diagnosis and treatment of cerebrovascular disease. Awareness of the anatomic variations that may be encountered, common and uncommon, is necessary to avoid diagnostic pitfalls and to avert therapeutic disasters. Careful anatomic analysis and understanding of collateral pathways and dangerous anastomoses facilitates cross-sectional and angiographic diagnosis and the development of surgical and endovascular treatment strategies.