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Pterygoid Venous Plexus

plexus venosus pterygoideus

The pterygoid venous plexus is a network of veins embedded within the infratemporal fossa between and around the medial and lateral pterygoid muscles. It drains the infratemporal fossa, the deep face, the temporal fossa, and the nasal cavity via the posterior nasal veins, and communicates with the cavernous sinus via emissary veins through the foramen ovale and foramen lacerum, with the facial vein via the deep facial vein, and with the maxillary vein.

Region: Head & Skull

Clinical Relevance

Clinical Notes

The pterygoid venous plexus is the main hazard in posterior superior alveolar nerve (PSA) block and in injections targeting the pterygomandibular space and the maxillary nerve at the foramen ovale. Inadvertent intravascular injection into the plexus can cause haematoma in the infratemporal fossa producing trismus, or can allow spread of local anaesthetic to the cavernous sinus and orbit. The plexus provides the venous drainage pathway by which pterygomaxillary space infections can reach the cavernous sinus intracranially.

Pathology

Common Injuries & Conditions

Infratemporal Haematoma from PSA Block

The posterior superior alveolar nerve block injected too posteriorly into the infratemporal fossa penetrates the pterygoid plexus, causing rapid haematoma formation that presents as progressive painless cheek swelling and trismus within minutes of injection, managed with ice, NSAIDs, and observation for infection.