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Topic

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Foramen ovale

The foramen ovale is an oval-shaped opening in the posterior part of the sphenoid bone within the middle cranial fossa. It serves as a passageway connecting the cranial cavity with the infratemporal fossa, allowing the mandibular nerve (V3, the third branch of the trigeminal nerve), accessory meningeal artery, lesser petrosal nerve, and emissary veins to pass through. The foramen is bordered anteromedially by the sphenoid body and posterolaterally by the greater wing of the sphenoid, with its dimensions and shape varying slightly among individuals. Its position and size are critical anatomical landmarks in neurosurgical procedures, skull base imaging, and trigeminal nerve interventions.

Synonyms

  • Ovale foramen

  • Foramen sphenoidale ovale

  • Cranial foramen ovale

Function

  • Provides a conduit for the mandibular nerve (V3) and associated vessels

  • Allows passage of the lesser petrosal nerve for parasympathetic fibers

  • Enables emissary veins to connect intracranial and extracranial venous systems

  • Acts as a landmark for neurosurgical navigation and trigeminal nerve procedures

MRI Appearance
T1-weighted images:

  • The foramen ovale appears as a small, oval hypointense opening within the sphenoid bone

  • Surrounded by hyperintense marrow fat in the sphenoid bone, providing natural contrast

  • Neural and vascular structures within the foramen may appear isointense to soft tissue

  • Pathology, such as nerve sheath tumors or meningeal lesions, may appear as altered signal intensity or enlargement of the foramen

T2-weighted images:

  • Foramen ovale remains hypointense, with surrounding fat and soft tissues hyperintense

  • Useful for identifying nerve compression, inflammation, or perineural tumor spread

STIR (Short Tau Inversion Recovery):

  • Fat suppression highlights any edema or soft tissue pathology in the foramen

  • Normal bony margins are hypointense; abnormal soft tissue is hyperintense

CT Appearance

  • The foramen ovale is well-demarcated on bone window images as an oval hypodense opening in the greater wing of the sphenoid

  • Surrounding dense sphenoid bone appears hyperdense, providing clear contrast

  • Axial, coronal, and sagittal planes allow precise assessment of size, shape, and bony margins

  • CT is particularly useful for detecting congenital variations, fractures, or bony erosions from tumors or infection

MRI images

Foramen ovale mri axial image -img-00000-00000