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Brachium of superior colliculus

The Brachium of the Superior Colliculus is a prominent white matter tract located in the midbrain, specifically connecting the lateral geniculate body (LGB) of the thalamus to the superior colliculus. This structure is involved in the visual and oculomotor pathways, relaying information critical for visual reflexes and spatial orientation. It appears as a compact bundle on cross-sectional neuroimaging, contributing significantly to midbrain neuroanatomy and clinical imaging interpretation.

Synonyms

  • Brachium colliculi superioris

  • Superior collicular brachium

  • Brachium of the optic tract (context dependent)

Arterial Supply

  • Branches of the posterior cerebral artery (main supply)

  • Branches of the superior cerebellar artery

  • Branches of the posterior choroidal artery (minor supply)

Venous Drainage

  • Drained by the lateral mesencephalic vein

  • Venous blood ultimately drains into the basal vein of Rosenthal and the great cerebral vein (vein of Galen)

Function

  • Acts as a conduit for visual information from the lateral geniculate body to the superior colliculus

  • Involved in reflex visual tracking, coordinating head and eye movements in response to visual stimuli

  • Plays a role in visuomotor integration and orientation responses

MRI Appearance

  • T1-weighted MRI: Appears as a small, well-defined area of intermediate to low signal intensity in the dorsal midbrain

  • T2-weighted MRI: Shows slightly hyperintense signal relative to surrounding midbrain structures, but typically isointense to other white matter tracts

  • FLAIR: The brachium is not distinctly visualized; it remains isointense to surrounding white matter unless there is a pathological process

CT Appearance

  • On non-contrast CT, the brachium of the superior colliculus is not individually distinguishable from adjacent midbrain tissue

  • Appears as a part of the midbrain parenchyma, showing the same density as neighboring white matter tracts

  • May be better appreciated on high-resolution or thin-slice CT when evaluating for midbrain pathology

MRI images

Brachium of superior colliculus mri axial image