Corpus: Emissary vein
1. Definition
Emissary veins are short-circuit connections between the superficial cranial veins of the skull, the diploic veins, and the venous sinuses of the brain.
2. Veins
- Parietal emissary vein (paired): superficial temporal vein <-> superior sagittal sinus
- Mastoid emissary vein (paired): occipital vein <-> sigmoid sinus
- Condylar emissary vein: external vertebral venous plexus <-> sigmoid sinus
- Occipital emissary vein: external vertebral venous plexus <-> sigmoid sinus
3. Function
Emissary veins, along with other extracranial veins, help equalize pressure and regulate temperature inside the skull
4. Clinical relevance
Emissary veins lack venous valves, allowing bidirectional blood flow. This means blood from extracranial veins can flow back into the dural venous sinuses. Inflammation in the superficial inflow areas (such as boils on the scalp) can lead to (septic) sinus thrombosis if pathogens spread to the cerebral sinuses.