Corpus: Hypoglossal emissary vein

The emissary veins are venous connections that create short-circuit pathways between the superficial veins of the cranial vault, the diploic veins, and the dural venous sinuses of the brain.

• Parietal emissary vein (paired): Connects the superficial temporal vein with the superior sagittal sinus.
• Mastoid emissary vein (paired): Links the occipital vein with the sigmoid sinus.
• Condylar emissary vein: Connects the external vertebral venous plexus with the sigmoid sinus.
• Occipital emissary vein: Also connects the external vertebral venous plexus with the sigmoid sinus.

Emissary veins play a role in equalizing pressure and regulating temperature within the skull by providing alternative venous drainage pathways between intracranial and extracranial venous systems.

Emissary veins lack venous valves, allowing for bidirectional blood flow. This characteristic enables blood from extracranial veins to potentially flow back into the dural venous sinuses. Consequently, infections in the superficial areas of the scalp, such as boils, can spread through these veins and lead to septic sinus thrombosis if the pathogens reach the cerebral sinuses.