Cerebellum – Balance & Motor Control in Brain

Brain Centre for Movement Control, Equilibrium & Muscle Tone

Nov 8, 2009

The cerebellum, with its rich neural network, is the brain center responsible for motor control over voluntary muscles, muscle tone and maintenance of balance

Although called “little brain” (cerebellum in Latin), the major role played by the cerebellum in motor control, equilibrium, balance and muscle tone is now recognized. The cerebellum is a part of the central nervous system with a rich neural network that regulates movement control by influencing timing in motor activities and smooth and rapid progression between movements.

Cerebellum and its Neural Network

The cerebellum is about fist sized and hidden below and behind the cerebral cortex of the brain. While this location protects the cerebellum from injury, this concealed position and its size belie its true capacity. It was for long thought to be a ‘silent area’ of the central nervous system as it did not respond to electrical stimulation with any motor movement.

The cerebellum actually comprises of more neurons (nerve cells) than the rest of the brain put together and receives about 200 million incoming neural connections. That is a lot of information to process, considering the optic nerve which transmits continuous visual input to the brain is only composed of 1 million nerve fibers.

Grossly, the cerebellum is divided into 3 lobes - an anterior, a posterior and a flocculonodular lobe. It has gray and white matter regions just like the cerebral cortex.

Functions of the Cerebellum

Cerebellum and Muscle Tone

The cerebellum has neural connections with other parts of the brain and the peripheral parts of the body. So at any given moment it continuously receives sensory information from the bones, joints and muscles about their position, rate and direction of movement and forces acting on them.

The cerebellum in turn conveys this information to the motor control centers of the cortex (motor cortex) setting the background tone and posture so that the cortex can execute new movements based on intent. In other words, the cerebellum tells the motor cortex in what position a limb already is and what it is doing so the cortex can plan its next move.

Cerebellum and Motor Control

The cerebellum also continuously receives information on the sequence of movements desired by the motor control areas of the cortex. With regard to movement coordination, the cerebellum behaves like a computer, constantly comparing the actual movement of the muscle groups with the motions intended by the motor cortex.

In case of a difference between the two, the cerebellum immediately sends signals to the muscle groups to correct the movement so that the desired effect can be achieved, much like computers calculating and correcting the flight path of airplanes or space vehicles.

Cerebellum, Balance and Ataxia

The body maintains its equilibrium from sensory inputs from the eyes, the vestibular system in the ears, the proprioceptive system (joints, bones and muscles) regarding the position of the body with respect to the external environment. The flocculonodular lobes of the cerebellum play an important role in receiving and processing this information. This is why cerebellar injury results in ataxia and an abnormal gait.

Literally every movement of the body, although planned and executed by the motor cortex of the central nervous system, is regulated and smoothly controlled by the cerebellum. The cerebellum plays a truly magnificent role in motor control and maintenance of balance.

Carpenter's Human Neuroanatomy. 9th ed. Parent A, Carpenter MB. Philadelphia: Williams and Wilkins; 1995.

The copyright of the article Cerebellum – Balance & Motor Control in Brain in Nervous System is owned by Lakshmi Ananth. Permission to republish Cerebellum – Balance & Motor Control in Brain in print or online must be granted by the author in writing.