Vermis of cerebellum

Vermis of cerebellum is the central, constricted part of cerebellum which connects the two hemispheres with each other. A distinct paramedian fissure, on either side, separates the vermis from the cerebellar hemispheres.

Due to the emergence of various transverse fissures in a mediolateral plane, the vermis of cerebellum and its hemispheres get divided into several lobes and lobules, with each lobule being further sub-divided into folia (or leaflets). The lobules of vermis of cerebellum have been labelled from I to X as per the Larsell’s Roman-numeral numbering system, which is homologous to the classic nomenclature.

The anterior lobe of cerebellum–in front of the primary fissure–contains lobules I-V of vermis (Larsell’s classification), which are also called as ‘Lingula’, ‘Central lobe’ and ‘Culmen’ in the vermis, as per the classic nomenclature.

When it comes to the middle (or posterior) lobe–behind the primary fissure–it contains the Larsell’s lobules VI-IX of vermis of cerebellum. The lobule VI is given the name ‘Declive’, in the classic nomenclature. Similarly, lobule VIIA and VIIB are the same as ‘Folium’ and ‘Tuber’ in the classic nomenclature. Larsell’s lobule VIII is the same as ‘Pyramid’ (as per classic nomenclature). Moreover, Larsell’s lobule IX is equivalent to ‘Uvula’; as per the classic nomenclature.

Lastly, in the flocculonodular lobe (or vestibulocerebellum)–behind the posterolateral fissure–Larsell’s lobule X of the vermis of cerebellum has been named ‘nodulus’–both under Bolk’s classification system and as per the classical paradigm. The cortical tissue is devoid between the vermis and the hemispheres of cerebellum in this region.

The vermis of cerebellum and (paramedian region of) cerebellar hemispheres, receive proprioceptive information (via spinocerebellar pathways) about the actual movement occurring in real-time. The data about the predicted or the intended plan of voluntary movement–that has been originally formulated in the cerebral cortex–reaches cerebellum via corticopontocerebellar pathways. Next, the predicted plan is matched with the ‘actual’ movement happening in real-time. Consequently, any mismatch between the intended plan and the actual plan could be corrected by the cerebellum at a subconscious level, thus contributing to the precision, accuracy, planning and timing of voluntary movements.

Please note that vermis is concerned with controlling the axial body musculature. A stroke in the vermis of cerebellum could lead to motor incoordination and axial body ataxia.