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Topic

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Foramen spinosum

The foramen spinosum is a small, circular bony opening located in the greater wing of the sphenoid bone within the middle cranial fossa. It is situated posterolateral to the foramen ovale and anteromedial to the spine of the sphenoid, forming a crucial conduit between the cranial cavity and infratemporal fossa. The foramen transmits the middle meningeal artery, middle meningeal vein, and the meningeal branch of the mandibular nerve (V3), making it an important landmark in neurosurgical procedures, skull base imaging, and trauma assessment. Its size and shape can vary, and it may occasionally present with accessory foramina.

Synonyms

  • Spinosal foramen

  • Sphenoidal spinosum

  • Foramen of the sphenoid spine

Function

  • Provides a passageway for the middle meningeal artery and vein, supplying the dura mater

  • Transmits the meningeal branch of the mandibular nerve (V3)

  • Acts as a bony landmark in the middle cranial fossa for neurosurgical orientation

  • Contributes to structural anatomy of the sphenoid bone and skull base

MRI Appearance
T1-weighted images:

  • Appears as a tiny hypointense or signal-void structure within the greater wing of the sphenoid due to its bony nature

  • Surrounded by intermediate-to-hyperintense soft tissues in the infratemporal fossa

  • Vascular structures within the foramen are typically isointense to surrounding soft tissue, though small size may make them difficult to resolve

T2-weighted images:

  • Bony margins remain hypointense, while vascular structures may show slightly hyperintense signal if blood flow is slow

  • Useful for detecting vascular anomalies, dural arteriovenous fistulas, or inflammatory changes in adjacent tissues

STIR (Short Tau Inversion Recovery):

  • Fat suppression highlights surrounding soft tissues in the infratemporal fossa

  • Normal bony foramen remains signal void, while adjacent soft tissue pathology appears hyperintense

CT Appearance

  • Foramen spinosum appears as a small, round-to-oval hyperdense opening in the greater wing of the sphenoid

  • Easily identified on axial and coronal planes; size typically ranges from 1–3 mm

  • Middle meningeal artery can sometimes be inferred as a small hypodense channel within the foramen

  • CT is ideal for evaluating skull base fractures, congenital variations, or accessory foramina

MRI images

Foramen spinosum mri axial image -img-00000-00000