Anatomy, Head and Neck, Emissary Veins

Emissary veins are valveless venous structures that connect the extracranial vessels of the scalp to the intracranial dural venous sinuses and diploic veins. The presence and distribution of emissary veins vary from person to person, and during childhood, these venous structures are found more frequently and with larger foramina. The valveless nature of these vessels facilitates bidirectional blood flow, which allows for the equalization of intracranial pressures and selective cooling of the brain. During times of pathologically elevated intracranial pressure, the emissary veins may serve as ‘safety valves.’ Emissary veins may serve as essential sources of perioperative bleeding and thrombosis, as well as have the potential to provide a dangerous pathway for infection to reach deep intracranial structures.