Emissary veins

Anatomical structures connecting the venous sinuses of the dura mater with veins outside the skull

Diagram of the emissary veins connecting the dural venous sinuses with veins outside the skull.

Emissary veins are valveless veins that pass through foramina in the skull and connect the venous sinuses of the dura mater with veins outside the skull. These veins play a role in the regulation of intracranial pressure and temperature, and they can also serve as potential pathways for the spread of infection.

Anatomy

Emissary veins are found in various locations throughout the skull. Some of the key emissary veins include:

• Parietal emissary vein: This vein passes through the parietal foramen and connects the superior sagittal sinus with veins of the scalp.
• Mastoid emissary vein: It traverses the mastoid foramen and links the sigmoid sinus with the posterior auricular vein or the occipital vein.
• Condylar emissary vein: This vein passes through the condylar canal and connects the sigmoid sinus with the suboccipital venous plexus.
• Occipital emissary vein: It passes through the occipital foramen and connects the confluence of sinuses with the external vertebral venous plexus.

Function

Emissary veins serve several important functions:

• Pressure regulation: They help equalize pressure between the intracranial and extracranial venous systems.
• Temperature regulation: By allowing blood to flow between the scalp and the cranial cavity, they help in dissipating heat.
• Pathway for infection: Due to their valveless nature, emissary veins can allow infections to spread from the extracranial to the intracranial regions, potentially leading to conditions such as meningitis or cerebral abscess.

Clinical significance

The presence of emissary veins can have clinical implications, particularly in the context of head trauma or surgery. They can be a source of bleeding during surgical procedures involving the skull. Additionally, their role as potential conduits for infection makes them clinically significant in cases of scalp infections or sinusitis.

Related pages

• Dural venous sinuses
• Cerebral veins
• Intracranial pressure
• Meningitis