Biventral lobule

At a glance

English

Biventral lobule

Latin (TA2)

Lobulus biventer

System

Brain and spinal cord

Region

Head

Side

Paired, left and right

About the biventral lobule

The biventral lobule (lobulus biventer) is a part of the posterior lobe of the cerebellum on the inferior surface of each hemisphere. It takes its name from the fissure that divides it into two parts, giving it two 'bellies'. In Larsell's numbered scheme it corresponds to hemispheric lobule VIII (H VIII), and in the vermis it is matched by the pyramis.

On the inferior surface it lies between the gracile lobule behind and the tonsil in front and medially. The tonsil, a rounded lobule next to the midline, sits just medial to it above the foramen magnum. The intrabiventral fissure runs across the lobule and separates its two parts, which are labelled H VIIIA and H VIIIB. Like the rest of the cerebellar cortex it is folded into transverse folia over a core of white matter.

Lobule VIII, in both vermis and hemisphere, carries a second map of the body, separate from the main one in the anterior lobe, and receives input through the spinocerebellar and pontine pathways. Functional imaging shows it active during movement of the limbs. Through the cerebellar nuclei its output influences the timing and coordination of movement on the same side of the body.

Because the biventral lobule lies close to the tonsil above the foramen magnum, it is part of the region seen in descriptions of tonsillar herniation and Chiari malformations. Disease of the hemisphere here causes limb incoordination on the same side, such as an intention tremor or past-pointing.

Function and supply

Function

Takes part in the coordination of limb movement on the same side of the body, carrying a secondary map of the body.

Blood supply

Mainly the posterior inferior cerebellar artery, with the anterior inferior cerebellar artery supplying the more lateral parts.