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Secondary fissure

The secondary fissure of the cerebellum is an anatomical groove found on the inferior surface of the cerebellum. It is one of the principal fissures dividing the cerebellar hemispheres into distinct lobes. Specifically, the secondary fissure separates the posterior lobe (neodermis) from the flocculonodular lobe (archicerebellum). This fissure plays a key role in cerebellar topography and is essential for understanding both functional neuroanatomy and radiological assessment. Though subtle, it is often referenced in anatomical and neuroimaging studies for cerebellar segmentation.

Synonyms

  • Fissura secundaria cerebelli (Latin)

  • Fissura secundaria

  • Secondary cerebellar fissure

Arterial Supply

  • Supplied predominantly by branches of the posterior inferior cerebellar artery (PICA)

  • Some regions near the secondary fissure may also receive small branches from the anterior inferior cerebellar artery (AICA)

  • Minor contributions possible from the superior cerebellar artery (SCA) at the periphery

Venous Drainage

  • Drained mainly by the inferior cerebellar veins

  • These veins ultimately empty into the transverse, straight, or occipital sinuses

  • Inferior vermian veins may be involved in draining the region adjacent to the fissure

Function

  • The secondary fissure itself is an anatomical landmark; it does not have a direct function

  • Functionally, the regions it separates are involved in:

    • Posterior lobe: Fine motor coordination, planning, and execution of movement

    • Flocculonodular lobe: Balance and eye movements (vestibular functions)

  • Helps define functional zones during cerebellar mapping

MRI Appearance

  • Appears as a hypointense (dark) linear groove on T1-weighted images and a hyperintense (bright) groove on T2-weighted images

  • Best visualized in sagittal and axial planes of high-resolution MRI, especially on thin-section anatomical sequences

  • Separates the posterior lobe from the flocculonodular lobe, visible as a distinct line between different folia (cerebellar folds)

  • May be accentuated with 3D volumetric imaging

CT Appearance

  • Typically not well visualized on standard CT due to limited soft tissue contrast

  • May be suggested by the separation between cerebellar lobes, visible as subtle hypodense (dark) lines in optimal conditions

  • CT is not the modality of choice for assessing cerebellar fissures but may occasionally show the fissure in very thin, high-resolution bone algorithm images

MRI images

Secondary fissure MRI 3T axial image

MRI images

Secondary fissure MRI 3T sagittal image

CT image

Secondary fissure of cerebellum CT sag anatomy image -img-00001-00001