Emissary veins passing through the foramen ovale, jugular foramen, foramen lacerum, and hypoglossal canal. Because the emissary veins are valveless, they are an important part in selective brain cooling through bidirectional flow of cooler blood from the evaporating surface of the head. In general, blood flow is from external to internal but the flow can be altered by increased intracranial pressure. A type of emissary vein goes through the sphenoidal emissary foramen inferior to the zygomatic arch with the cavernous sinus on the inside of the skull. This is an important route for spread of infection because cranial nerve VI and the
Lesional demyelinations of the central nervous system ventricles within the brain. This morphologic appearance was named Dawson's fingers by Charles Lumsden, after the Scottish pathologist James Walker Dawson, who first defined the condition in 1916. "Dawson's fingers" is the name for the lesions around the ventricle-based brain veins of patients with multiple sclerosis. The condition is thought to be the result of inflammation or mechanical damage by blood pressure around long axis of medular veins. Dawson's fingers spread along, and from, large periventricular collecting veins, and are attributed to perivenular inflammation. Lesions far away from these veins are known as Steiner's splashes. Sometimes experimental autoimmune encephalomyelitis has