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Topic

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Red nucleus

The red nucleus is a prominent, rounded structure located in the rostral midbrain tegmentum, just dorsal to the substantia nigra and medial to the cerebral peduncles. Named for its reddish hue in fresh specimens due to rich vascularity and iron content, the red nucleus plays a key role in motor coordination. It is a vital relay center for the rubrospinal tract and receives significant cerebellar input, integrating information necessary for limb movement and postural control. Recognizing the red nucleus is essential for understanding both normal and pathological conditions of the midbrain on neuroimaging.

Synonyms

  • Nucleus ruber

  • Ruber nucleus

Arterial Supply

  • Supplied mainly by branches of the posterior cerebral artery (PCA), particularly the paramedian branches.

  • Additional supply from branches of the posterior choroidal arteries.

  • Small perforating arteries from the basilar artery may also contribute.

Venous Drainage

  • Drained by the basal vein of Rosenthal.

  • Additional drainage to the great cerebral vein (vein of Galen).

Function

  • Involved in motor coordination, particularly of the upper limbs.

  • Integrates cerebellar and cortical motor signals.

  • Relays signals via the rubrospinal tract to the spinal cord (prominent in animals; less in humans, but still functional).

  • Plays a role in flexor muscle tone regulation.

  • Participates in the modulation of movement and some aspects of cognitive functions via connections with the cerebellum.

MRI Appearance

  • T2-weighted images:

    • Red nucleus appears as a round to oval structure of intermediate to low signal intensity due to its iron content.

    • Stands out against the high signal of surrounding tegmentum.

  • T1-weighted images:

    • Typically isointense to slightly hypointense compared to adjacent midbrain structures.

    • Borders are clear, but contrast may be subtle.

  • FLAIR sequence:

    • Generally appears isointense to the surrounding tissue, but may be slightly hypointense.

    • Lesions or abnormal signal (e.g., demyelination, infarction) may highlight the nucleus.

CT Appearance

  • On non-contrast CT, the red nucleus is difficult to delineate due to lack of contrast with surrounding midbrain structures.

MRI images

Red nucleus mri 3t axial image

MRI images

Red nucleus mri 3t sagittal image