Cerebellar Vermis: Topography and Variations

Abstract

The vermis is described as the unpaired, median portion of the cerebellum to which the hemispheres are attached. Both the vermis and the hemispheres are formed by folia that, grouped together, are called lobules. The material analyzed consisted of a sample made up of 43 adult male cerebella fixed in 10% formaldehyde and sliced medially. The lingula was attached to the superior medullary velum in 100% (43) of the cerebella, varying only in size. In 80% (32) of the cerebella, the central lobe contained one folium; 7.5% (3) had two folia with the first larger than the second; 10% (4) had two folia with the second larger than the first; and 2.5% (1) had two folia of equal size. In 5% (2) of the cerebella, the folium of the vermis emerged from the declive; in 47.5% (19), the folium emerged from the central white matter; and in 42.5% (17), the folium emerged from the tuber. There was no variation in the lobules, culmen, pyramid, uvula or nodule in the sample studied. Contrary to what many believe, the folia of the cerebellum exhibit variations in form, number and arrangement. However, these variations are virtually unreported, which often hinders the determination of the limits of these structures by students of anatomy of the cerebellum.