The pterygoid plexus of veins becomes the maxillary vein.

Emissary veins (from the cavernous sinus to the pterygoid plexus)

Some vortex veins drain into the inferior orbital vein which drains into the pterygoid plexus.

These connect the extracranial pterygoid plexus with the intracranial cavernous sinus and present an unopposed route for infection.

There are also connections with the pterygoid plexus of veins via inferior ophthalmic vein, deep facial vein and emissary veins.

If at all present, the sphenoidal emissary foramen gives passage to a small vein (vein of Vesalius) that connects the pterygoid plexus with the cavernous sinus.

The pterygoid plexus is a venous plexus of considerable size, and is situated between the temporalis muscle and lateral pterygoid muscle, and partly between the two pterygoid muscles.

They may be significant however, as it is possible for infection to spread via emissary veins from the pterygoid plexus to the cavernous sinus, which may result in cavernous sinus thrombosis, a rare but life-threatening condition.

It is formed by a confluence of the veins of the pterygoid plexus, and passes backward between the sphenomandibular ligament and the neck of the mandible, and unites with the superficial temporal vein to form the retromandibular vein.