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Pterygoid venous plexus

The Pterygoid Venous Plexus is an extensive network of small veins situated in the infratemporal fossa, deep to the ramus of the mandible and lateral to the lateral pterygoid muscle. It plays a vital role in the venous drainage of the deep face, receiving blood from regions such as the nasal cavity, paranasal sinuses, palate, teeth, muscles of mastication, and the nasopharynx. The plexus communicates with the cavernous sinus and drains primarily into the maxillary vein. Due to its complex anatomical relationships, it is significant in the spread of facial infections, dental pathology, and during head and neck interventions.

Synonyms

  • Pterygoid plexus

  • Pterygoid venous network

  • Venous plexus of the infratemporal fossa

MRI Appearance of the Pterygoid Venous Plexus

  • PD (Proton Density) Sequence:

    • The plexus appears as a cluster of tubular or serpiginous low-signal intensity channels, isointense to other venous structures.

    • The signal may be slightly higher than surrounding muscles due to slow venous flow.

    • Flow voids can sometimes be seen, especially if the veins are large or if the patient moves during the scan.

  • STIR (Short Tau Inversion Recovery) Sequence:

    • The plexus usually demonstrates low to intermediate signal intensity.

    • The STIR sequence is useful for identifying adjacent inflammatory or edematous changes, but the venous plexus itself remains dark due to the suppression of fluid signal.

    • Edema or inflammation involving the pterygoid muscles may enhance visualization of the plexus by contrast.

  • T1-Weighted Sequence:

    • The pterygoid venous plexus appears as low-signal intensity structures within the infratemporal fossa, matching the signal of blood in other veins.

    • When intravenous gadolinium contrast is used, the plexus enhances and becomes more conspicuous, helping to distinguish it from surrounding muscles and fat.

    • Thrombosed veins, if present, will appear as regions of altered signal—often isointense or hyperintense on T1 depending on the stage of thrombus.

MRI images

Pterygoid venous plexus MRI image