Emissary veins

Source: Wikipedia, the free encyclopedia.
Emissary veins
Details
Identifiers
Latinvena emissaria
TA98A12.0.00.033
A12.3.05.301
TA24872
FMA50790
Anatomical terminology

The emissary veins connect the extracranial venous system with the intracranial venous sinuses. They connect the

diploic veins within the skull.[1]

Emissary veins have an important role in selective cooling of the head. They also serve as routes where infections are carried into the cranial cavity from the extracranial veins to the intracranial veins.

There are several types of emissary veins including the posterior condyloid, mastoid, occipital and parietal emissary veins.[1]

Structure

There are also emissary veins passing through the foramen ovale, jugular foramen, foramen lacerum, and hypoglossal canal.[citation needed]

Coronal cross section of skull showing venous drainage, with emissary vein uppermost

Function

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[2] but the flow can be altered by increased intracranial pressure.

Clinical significance

One notable emissary vein, the

internal carotid pass through the cavernous sinus, with cranial nerves III, IV, V1, and V2 passing alongside the lateral wall of the sinus. Subsequent infection or inflammation in the cavernous sinus can result in septic cavernous sinus thrombosis, with resultant damage to the cranial nerves contained within, as well as further spread of the infection leading to meningitis.[4]

Rupture of an emissary vein can result in a subgaleal hemorrhage, a rare but serious injury most often seen as a complication of vacuum extraction.[5]

See also

References