Anatomy of the cerebellum

The word cerebellum translates to little brain. Not because it’s the brain of a tiny animal or baby, but rather because of the fact that the cerebellum looks like a smaller version of the human cerebrum.

Very simply, the cerebellum assists with coordinating and adjusting voluntary movement. It plays a major role in posture, balance, maintenance of muscle tone and coordinating skilled voluntary motor activities - things like riding a bicycle, or for the more adventurous, walking a tightrope!

In order for the cerebellum to undertake these functions, it has to be in constant communication with the cerebral cortex. It also receives and sends signals to many other structures in the central and peripheral nervous systems, processing information about current movement and positional states in order to help refine, correct and improve the motion.

Now, the cerebellum sits in the posterior part of the cranium, called the posterior cranial fossa, and it is covered by the tentorium cerebelli, which separates the cerebellum from the occipital and temporal lobes of the brain. Anterior to the cerebellum lies the fourth ventricle, pons, and medulla oblongata.

Just like the cerebrum, the cerebellum consists of two hemispheres. These two hemispheres are connected by a narrow ridge in the middle called the vermis. From an inferior view, parallel to the vermis, there are two distinguishable lobules called the cerebellar tonsils.

The cerebellum can be divided into three lobes; the anterior lobe, the posterior lobe, and the flocculonodular lobe. From a superior view, we can identify the anterior lobe, functionally referred to as the spinocerebellum, which is responsible for the regulation of muscle tone and adjusting on-going movements. Posterior to the anterior lobe is the V shaped primary fissure.

From a superior view, and posterior to this primary fissure, is the posterior lobe, functionally referred to as the cerebrocerebellum, or pontocerebellum, which contains the horizontal fissure separating the superior and inferior surface of the cerebellum. The cerebrocerebellum is the largest part of the cerebellum, and is responsible for assisting in planning and programming of skilled or fine motor movements.