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Topic

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Posterior superior fissure

The posterior superior fissure of the cerebellum is a prominent anatomical groove on the superior aspect of the cerebellar hemisphere. It plays a key role in separating the cerebellar lobules and is important for neurosurgical orientation and neuroradiological interpretation. This fissure demarcates the boundary between the anterior lobe and the posterior lobe of the cerebellum on its dorsal surface, thus contributing to the functional and anatomical compartmentalization of the cerebellum.

Synonyms

  • Fissura posterior superior cerebelli (Latin)

  • Superior posterior fissure

  • Superior fissure (less commonly used, can be ambiguous)

  • Sometimes referred to as part of the primary fissure (though the primary fissure is distinct and more commonly referenced)

Arterial Supply

  • Superior cerebellar artery (SCA):

    • Main arterial supply to the superior surface of the cerebellum, including regions adjacent to the posterior superior fissure.

  • Branches from posterior inferior cerebellar artery (PICA):

    • Can contribute to adjacent cerebellar cortex, but less so than SCA in this region.

  • Arteriolar supply:

    • Small pial branches follow the fissure and supply the cortex along its margins.

Venous Drainage

  • Superior cerebellar veins:

    • Drain the dorsal surface, including fissures such as the posterior superior fissure.

  • Drainage route:

    • Veins empty into the straight sinus, transverse sinus, and occasionally the vein of Galen via the superior vermian vein.

Function

  • No independent functional role:

    • The fissure itself does not have a function, but it separates cerebellar lobules involved in different aspects of motor coordination, balance, and cognitive processing.

  • Landmark:

    • Serves as a crucial landmark for anatomical orientation during imaging and surgery.

MRI Appearance

  • T1 and T2 weighted imaging:

    • Appears as a dark linear structure (hypointense) separating the brighter (cortical) cerebellar folia.

    • Best seen in sagittal and coronal planes as a deep groove or sulcus on the dorsal (superior) cerebellar surface.

  • High-resolution sequences:

    • Fissure is accentuated by the contrast between the thin cortical gray matter and the underlying white matter.

  • No enhancement:

    • Does not enhance with contrast agents as it is an anatomical fissure, not a vascular structure.

CT Appearance

  • Non-contrast CT:

    • Visible as a thin hypodense (dark) line or groove on the cerebellar surface, particularly with high-resolution or thin-slice imaging.

    • More challenging to delineate compared to MRI due to lower soft tissue contrast.

  • Contrast-enhanced CT:

    • No specific enhancement.

    • May help define adjacent vasculature but the fissure itself remains a non-enhancing groove.

MRI images

Posterior superior fissure MRI 3T coronal image

MRI images

Posterior superior fissure MRI 3T sagittal image

CT image

Posterior superior fissure of cerebellum CT sag anatomy image -img-00001-00001