Quick Facts
The emissary vein is one of the small, valveless veins that pass through foramina of the skull, connecting the dural venous sinuses with scalp veins or with deep veins below the base of the skull (Dorland, 2011).
Related parts of the anatomy
Description
The emissary veins are small veins which pass through various foramina inside the skull to connect the intracranial venous sinuses with the extracranial veins, often via a network of diploic veins. Learning their anatomy has clinical implications as these venous channels could provide a route for the spread of infection from outside the cranium into the venous sinuses intracranially. For instance, the spread of infection from the paranasal sinuses to the cavernous sinus.
Examples of a few important emissary veins have been given below:
—mastoid emissary vein interconnects auricular or occipital veins from suboccipital venous plexus with the sigmoid sinus;
—parietal emissary vein interconnects the veins of the scalp with the superior sagittal sinus;
—condylar emissary vein interconnects the sigmoid sinus and veins of the suboccipital triangle;
—occipital emissary vein interconnects the confluence of sinuses with the occipital vein;
—venous plexus of foramen ovale interconnects the cavernous sinus and the pterygoid plexus of veins;
—internal carotid venous plexus interconnects the internal jugular vein and cavernous sinus;
—an emissary vein through the sphenoidal foramen (of Vesalius) and the venous plexus of foramen lacerum interconnect the cavernous sinus and the pharyngeal veins and pterygoid plexus.
The ophthalmic veins are potentially emissary veins, as they interconnect intra- and extracranial veins.
It should be noted that emissary veins are valveless channels and, hence, the venous blood can flow in either direction (Tubbs, Shoja and Loukas, 2016; Mortazavi et al., 2012).
References
Dorland, W. (2011) Dorland's Illustrated Medical Dictionary. 32nd edn. Philadelphia, USA: Elsevier Saunders.
Mortazavi, M. M., Tubbs, R. S., Riech, S., Verma, K., Shoja, M. M., Zurada, A., Benninger, B., Loukas, M. and Cohen Gadol, A. A. (2012) 'Anatomy and pathology of the cranial emissary veins: a review with surgical implications', Neurosurgery, 70(5), pp. 1312-8; discussion 1318-9.
Tubbs, R. S., Shoja, M. M. and Loukas, M. (2016) Bergman's Comprehensive Encyclopedia of Human Anatomic Variation. Wiley.
