Folium of vermis

At a glance

English

Folium of vermis

Latin (TA2)

Folium vermis

System

Brain and spinal cord

Region

Head

Side

Single, on the midline

About the folium of vermis

The folium of the vermis is one of the lobules of the midline vermis of the cerebellum. It is short and narrow, often little more than a single leaf of cortex, which is the meaning of its Latin name. In the numbered scheme of Larsell it is the upper part of vermal lobule VIIA, the rest of which lies in the tuber.

It sits at the back of the upper surface of the vermis, where the upper and lower surfaces of the cerebellum meet. In front, the posterior superior fissure separates it from the declive. Behind and below, the horizontal fissure, which runs round the posterior and lateral margin of the cerebellum, separates it from the tuber of the vermis on the inferior surface. On each side the folium widens into the superior semilunar lobule of the hemisphere, the first crus of the ansiform lobule, and it is this hemispheric part that carries most of the cortex at this level.

Its cortex has the usual three cerebellar layers. As part of the posterior lobe vermis it projects through Purkinje cells mainly to the fastigial nucleus and so to the vestibular nuclei and the brainstem reticular formation. With the declive and the tuber, it forms the oculomotor region of the vermis, which helps to adjust the size of saccadic eye movements and to keep gaze accurate.

Because the folium is so small, it is rarely damaged in isolation. Disease of the vermis as a whole, as in alcohol-related cerebellar degeneration, which affects the upper vermis most, mainly produces a broad-based, unsteady gait.

Function and supply

Function

Part of the posterior lobe vermis concerned with balance, posture and the accuracy of rapid eye movements.

Blood supply

Branches of the superior cerebellar artery on the upper surface; the posterior inferior cerebellar artery supplies the vermis just below.