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Venous plexus of foramen ovale

The venous plexus of the foramen ovale is a small but clinically important network of veins located at the skull base, specifically traversing the foramen ovale in the greater wing of the sphenoid bone. This plexus serves as a key venous communication between the extracranial pterygoid venous plexus and the intracranial cavernous sinus. Understanding its anatomy, synonyms, and imaging characteristics is essential for accurate interpretation of neuroimaging, surgical planning, and avoiding diagnostic pitfalls.

Synonyms:

  • Foramen ovale venous plexus

  • Plexus venosus foraminis ovalis

  • Skull base venous plexus of the foramen ovale

Function:

  • Acts as a venous conduit between the extracranial pterygoid venous plexus and the intracranial cavernous sinus.

  • Facilitates venous drainage of the deep face and skull base regions.

  • May provide an alternative route for intracranial-extracranial venous communication.

  • Can serve as a potential pathway for the spread of infection or tumor from the face to the cranial cavity.

MRI Appearance

  • T1-weighted (T1W)

    • Appears as a small, well-defined hypointense (low signal) area within the foramen ovale.

    • May be inconspicuous unless enlarged or if there is adjacent pathology.

  • T2-weighted (T2W)

    • Typically appears as a hypointense (low signal) structure due to flow void of venous blood.

    • The low signal is characteristic of fast-flowing or even sometimes slow-flowing venous structures at the skull base.

  • 3D Phase-Contrast (PC 3D)

    • Flow-sensitive sequence; venous flow within the plexus is visualized as a flow-related signal.

    • Helps demonstrate patency and directionality of venous flow.

  • Post-contrast T1-weighted

    • The plexus enhances vividly after gadolinium contrast administration, appearing as a small enhancing venous structure.

CT and CTV Appearance:

  • CT (Non-Contrast):

    • The venous plexus itself is typically not visible unless dilated or thrombosed.

    • The foramen ovale may appear widened if the plexus is prominent.

  • CT Venography (CTV):

    • Demonstrates enhancing venous channels traversing the foramen ovale, connecting extracranial and intracranial venous systems.

    • Tubular or plexiform enhancing structures may be seen coursing through the foramen ovale, especially on multiplanar reconstructions.

MRI images

Venous plexus of foramen ovale MRI 3T axial image

MRI images

Venous plexus of foramen ovale MRI 3T coronal image