pterygoid venous plexus
The pterygoid venous plexus is a small intercommunicating cluster of venules that is intimately related to the lateral pterygoid muscle, lying both intramuscularly and around the muscle.
The plexus is formed by very small veins that are the venous counterparts to the branches of the maxillary artery. However, most of the blood draining from the tissues supplied by this artery bypasses the plexus, instead passing back to the systemic circulation via the facial, pharyngeal, and diploic veins.
The veins of the pterygoid plexus have valves, and the plexus acts as a small pump assisting the return of blood by the contractions of the lateral pterygoid muscle.