Corpus: Emisssary vein
1. Definition
Emissary veins are venous short-circuit connections between the superficial cranial veins of the cranial vault, the diploic veins, and the blood-conducting sinuses of the brain.
2. Veins
- Parietal emissary vein (paired): Connects the superficial temporal vein to the superior sagittal sinus
- Mastoid emissary vein (paired): Connects the occipital vein to the sigmoid sinus
- Condylar emissary vein: Connects the external vertebral venous plexus to the sigmoid sinus
- Occipital emissary vein: Connects the external vertebral venous plexus to the confluence of sinuses
3. Function
Emissary veins, along with other extracranial veins, serve to 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 sinuses. If there is an infection in the superficial inflow areas (e.g., boils on the scalp), the pathogen can spread to the cerebral sinuses, leading to (septic) sinus thrombosis.