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Nodule of vermis

The nodule of vermis is a small, rounded structure located at the anterior (ventral) end of the cerebellar vermis, part of the cerebellum. It is considered the most inferior and anterior portion of the vermis and is continuous laterally with the flocculus, together forming part of the flocculonodular lobe. The nodule is situated in the roof of the fourth ventricle, directly overlying it, and is covered by the thin layer of white matter known as the medullary velum. Functionally, it is important in maintaining balance and coordinating eye movements, as it is part of the vestibulocerebellum.

Synonyms

  • Nodulus (Latin: Nodulus vermis)

  • Nodular lobe

  • Nodule of the cerebellar vermis

  • Anterior nodule of vermis

Arterial Supply

  • Primarily supplied by branches of the Posterior Inferior Cerebellar Artery (PICA)

  • May also receive contributions from the Superior Cerebellar Artery (SCA) and Anterior Inferior Cerebellar Artery (AICA)

Venous Drainage

  • Drained mainly by the Superior and Inferior Vermian veins

  • Venous blood ultimately flows into the Great Cerebral Vein (Vein of Galen) and the Straight Sinus

Function

  • Integral component of the vestibulocerebellum (flocculonodular lobe)

  • Plays a key role in maintaining equilibrium and balance

  • Regulates vestibulo-ocular reflexes, contributing to coordination of eye movements

  • Modulates muscle tone and posture in response to vestibular (inner ear) input

MRI Appearance

  • Appears as a small, midline structure at the anterior vermis, just above the fourth ventricle

  • On T1-weighted images: Isointense to the rest of the cerebellar cortex

  • On T2-weighted images: Hyperintense cortex with a hypointense medullary center

  • Clearly delineated in sagittal and axial planes; best visualized in the mid-sagittal section as a rounded nodule at the roof of the fourth ventricle

  • Separation from the flocculus may be seen laterally

CT Appearance

  • Appears as a small, dense, midline cerebellar structure anteriorly and inferiorly, at the roof of the fourth ventricle

  • Cerebellar cortex appears slightly denser than surrounding CSF but may be difficult to distinguish in non-contrast studies due to limited soft tissue contrast

  • Bony landmarks and the fourth ventricle help with identification

  • Pathology (e.g., infarct, atrophy, tumors) may make it more conspicuous

MRI images

Nodule of vermis MRI 3T axial image

MRI images

Nodule of vermis MRI 3T coronal image

MRI images

Nodule of vermis MRI 3T sagittal image

CT image

Nodule of vermis CT sag anatomy image -img-00001-00001