Culmen

At a glance

English

Culmen

Latin (TA2)

Culmen

System

Brain and spinal cord

Region

Head

Side

Single, on the midline

About the culmen

The culmen, a word meaning summit, is the topmost part of the vermis, the narrow midline strip that joins the two cerebellar hemispheres. It belongs to the anterior lobe of the cerebellum and corresponds to lobules IV and V in the numbering of Larsell. In a midline section it is the large leaf-covered hump at the peak of the cerebellar outline, sitting under the tentorium cerebelli and below the occipital lobes.

In front it is separated from the central lobule by the preculminate fissure; behind, the deep primary fissure divides it from the declive, which is the first vermian lobule of the posterior lobe. On each side the culmen is continuous with the anterior quadrangular lobule of the hemisphere. Like all cerebellar cortex it is folded into thin transverse folia, each made of a molecular layer, a Purkinje cell layer and a granular layer over a core of white matter.

The anterior lobe vermis, including the culmen, is a main part of the spinocerebellum. It receives spinocerebellar fibres carrying information about the position and movement of the trunk and limbs, and it projects through the fastigial and interposed nuclei to brainstem motor centres. Its job is to tune posture, muscle tone and the coordination of the trunk and legs during standing and walking. The anterior lobe holds a body map, with the leg represented mainly in this region.

The anterior vermis is especially sensitive to long-term heavy alcohol use, and atrophy here produces a broad-based unsteady gait with relatively little arm or speech involvement. The culmen is also a common site of degeneration in some inherited ataxias.

Function and supply

Function

Helps control posture, muscle tone and coordination of the trunk and legs during standing and walking, using spinocerebellar input on body position.

Blood supply

Branches of the superior cerebellar artery.