Also emptying into the dural venous sinuses are diploic veins, which run between the internal and external tables of compact bone in the roof of the cranial cavity, and emissary veins, which pass from outside the cranial cavity to the dural venous sinuses (Fig. 8.43).
The emissary veins are important clinically because they can be a conduit through which infections can enter the cranial cavity because they have no valves.