Topics

Topic

design image
Inferior semilunar lobule

The Inferior Semilunar Lobule of the cerebellum is a distinct anatomical region situated on the inferior (ventral) surface of the cerebellar hemisphere. It is a prominent lobule that forms part of the posterior lobe, lying lateral to the uvula and medial to the tonsil. The inferior semilunar lobule curves around the lateral border of the cerebellum and is separated from the superior semilunar lobule above by the horizontal fissure. This region is involved in the coordination of voluntary motor activity and balance, integrating sensory and motor information from the body.

Synonyms

  • Lobulus semilunaris inferior (Latin term)

  • Lobulus semilunaris posterior

  • Posterior semilunar lobule

Arterial Supply

  • Mainly supplied by the Posterior Inferior Cerebellar Artery (PICA), a branch of the vertebral artery.

  • Additional minor contributions may come from the Anterior Inferior Cerebellar Artery (AICA), especially in some anatomical variants.

Venous Drainage

  • Drained by the inferior cerebellar veins.

  • These veins ultimately drain into the transverse sinus, sigmoid sinus, and straight sinus via the cerebellar venous system.

Function

  • Plays a key role in the coordination of limb movements and fine motor control.

  • Involved in regulating muscle tone and ensuring smooth execution of voluntary motor activities.

  • Participates in the integration of proprioceptive information for postural control and balance.

MRI Appearance

  • Appears as a well-demarcated region of the cerebellar cortex on MRI, especially on T1- and T2-weighted images.

  • The cortical gray matter is seen as a thin rim, while the underlying white matter appears hyperintense on T2.

  • The fissures separating the inferior semilunar lobule from adjacent lobules (horizontal fissure above and posterolateral fissure below) are clearly visualized.

  • On sagittal and axial images, the lobule can be identified by its characteristic curved shape.

CT Appearance

  • On non-contrast CT, the inferior semilunar lobule appears isodense to other cerebellar structures, with gray and white matter differentiation being less distinct than on MRI.

  • It is best identified by its anatomical location and relationship to nearby fissures and lobules.

  • The lobule may become more conspicuous in the presence of pathology (e.g., infarct, hemorrhage) involving the PICA territory.

MRI images

Inferior semilunar lobule MRI 3T axial image

MRI images

Inferior semilunar lobule MRI 3T coronal image

MRI images

Inferior semilunar lobule MRI 3T sagittal image

CT image

Inferior semilunar lobule CT sag anatomy image -img-00001-00001