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Basilar sulcus

The basilar sulcus is a prominent, median groove located on the ventral (anterior) surface of the pons, part of the brainstem. It is formed by the impression of the basilar artery as it ascends along the midline of the pons. This groove plays a significant role as an anatomical landmark and is closely related to major neurovascular structures. Its clear visualization is important in neuroimaging for assessing brainstem pathologies, vascular anomalies, or mass effects.

Synonyms

  • Median sulcus of pons

  • Basilar groove

  • Sulcus basilaris (Latin)

Function

  • Serves as a groove accommodating the basilar artery on the ventral surface of the pons.

  • Acts as a landmark for neuroanatomical orientation in imaging and surgery.

  • Separates the right and left basis pontis.

Arterial Supply

  • The basilar sulcus itself does not have a direct blood supply but contains the basilar artery, which is formed by the union of the vertebral arteries.

  • Branches of the basilar artery (e.g., pontine arteries) supply the pons and adjacent structures.

Venous Drainage

  • Drained by small pontine veins that empty into the basilar venous plexus.

  • The basilar venous plexus connects to the inferior petrosal and transverse sinuses.

MRI Appearance

  • T1-weighted imaging:

    • The basilar sulcus appears as a linear or slit-like low signal (hypointense) groove in the midline anterior pons, with the basilar artery visible as a flow void or as a flow-related signal.

  • T2-weighted imaging:

    • Appears as a hyperintense (bright) groove in the ventral pons; the basilar artery may appear as a flow void (dark linear structure) within the sulcus.

  • FLAIR:

    • The sulcus is usually seen as a CSF-filled (hyperintense) groove; basilar artery remains hypointense due to flow void.

CT Appearance

  • On non-contrast CT, the basilar sulcus appears as a faint, linear low-density groove at the midline of the anterior pons, sometimes obscured by the adjacent basilar artery.

  • The basilar artery may be seen as a high-density (hyperdense) linear structure within the sulcus if calcified or thrombosed.

MRI images

Basilar sulcus MRI 3T axial image