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What is the cerebellum?

If you encounter a gopher hole while hiking, you may have to step over it, briefly balancing on one leg, but notice how you do not instantly fall over, despite the imbalance of weight on your feet. The cerebellum, a structure often referred to as the “little” brain, is responsible for maintaining balance, posture and motor coordination. The cerebellum is a walnut-shaped structure located most posteriorly to the brain and is connected to the brainstem via bridging structures called peduncles.

The cerebellum can be divided into two hemispheres, each responsible for coordinating movements on their respective sides of the body. This is referred to as ipsilateral control. For example, the right hemisphere of the cerebellum helps balance the right side of your body. If you had damage to the right hemisphere of your cerebellum you would probably have difficulty balancing on your right leg, such as  when trying to step over a gopher hole.

Lobes of the cerebellum:

The vermis is a narrow central structure which connects the two hemispheres of the cerebellum and regulates posture and movement along the body’s midline. The vermis is integral to our ability to remain upright while walking. If your vermis was damaged, you would have to stand with your feet wider apart to remain upright.

The cerebellum can be further divided into lobes:

Figure 96 Lobes of the cerebellum; anterior (green); posterior (blue); flocculonodular (purple)

• Anterior lobe: coordinates leg movements
• Posterior lobe: coordinates fine motor (precise movement) coordination of the hands, feet and head
• Flocculonodular lobe: coordinates balance and eye movements, and has received information from the vestibular system located in the inner ear to aid in posture and balance