The cerebellum (Lat. little brain) forms about one-tenth of the brain’s volume. Its main role is to organize motor information sent to the muscles via neuronal electrical signals, so that our body movements are regulated and well-coordinated.
This so-called ‘little brain’ is in charge of the timing, planning, execution, and accuracy of our movements, as well as of the control of balance and posture of the human body.
A large portion of the function of the cerebellum is also involved in the cognitive processes in the brain.
Where Is the Cerebellum Located in the Human Skull?
The cerebellum is located at the back of the brain. It sits directly above the pons and spinal cord in the brain, i.e. right below the occipital lobe and the temporal lobes of the cerebral cortex.
The cerebellum is made up of billions of neurons that are interconnected with other regions of both the brain and spinal cord. In this way, they facilitate precise movements of the human body.
This region of the brain is also labeled as the rhombencephalon, or the hindbrain.
What Is the Function of the Cerebellum?
The cerebellum is involved in various processes of the human brain, which use the sensory information from all areas within the central nervous system, multiple sensory modalities (vestibular, visual, auditory & somatosensory systems), brainstem nuclei, and the spinal cord.
Its main functions are:
- Control and regulation of the balance (via its connection to the inner ear), i.e. coordination, precision, and timing of voluntary movements.
- Muscle tone
- Motor learning
- Participation in cognitive functions (control of speech)
- Control of emotions and emotional responses
What Is the Structure of the Cerebellum?
The cerebellum consists of two hemispheres. And just like the other brain structures, it’s also made of grey matter and white matter.
This small, but very active part of the brain can be further subdivided into anatomical lobes, cerebellar zones, and functional divisions.
What Are the Lobes of the Cerebellum and What Is Their Function?
The cerebellum consists of three lobes, divided into distinct regions according to their functions:
- Anterior lobe
- Posterior lobe
- Flocculonodular lobe
Anterior lobe
This cerebellar lobe is also labeled as spinocerebellum. It is located in both the central and the intermediate zone of the cerebellum.
The function of the anterior lobe is to process the sensory information from the upper and lower extremities, as well as the neural stimuli from the head, neck, and the trunk of our body. In this way, it regulates self-movement and the posture of our bodies.
Posterior lobe
This lobe (or neocerebellum) is located on the side of the cerebellar hemispheres, under the primary fissure.
Its main function is to regulate and control fine motor movements, such as the movement of fingers and wrists, writing, turning pages, using a computer keyboard, using cutlery, brushing teeth, tying shoelaces, etc.
Flocculonodular lobe
This cerebellar lobe receives information from the sensory stimuli about the movement of the head so that it can regulate and coordinate it with the movement of the eyes. In other words, it helps us stabilize our gaze during head rotation.
What Are the Zones of the Cerebellum and What Is Their Function?
There are three cerebellar zones, according to the organization of the cerebellar output pathways:
- Vermis
- Intermediate zone
- Lateral hemispheres
Vermis
The cerebellar vermis is the midline structure, named for its ‘wormlike’ appearance. It’s located in the middle of the cerebellum.
The vermis helps with the regulation of the muscle tone for maintaining body posture, as well as our ability to move from one point to another.
Intermediate zone
This zone is the center responsible for receiving sensory information from the cerebral cortex to plan movements that are about to occur, and as such, it regulates both the timing and coordination of movement.
Lateral hemispheres
The lateral hemispheres are the side structures and the largest structure of the cerebellum. They regulate procedural learning, i.e. actively support motor planning for the arms and legs while riding a bike, skiing, etc.
What Is the Functional Division of the Cerebellum?
According to the function, the cerebellum can be divided into three functional areas:
- Cerebrocerebellum
- Spinocerebellum
- Vestibulocerebellum
Cerebrocerebellum
This functional area of the cerebellum is formed by the lateral hemispheres. It receives sensory information from the spinal cord and the other structures of the cerebral cortex in order to regulate, control, and coordinate motor movements, as well as visually guided movements (reaching a stationary object, for example).
Spinocerebellum
This functional area of the cerebellum is formed by the vermis and the middle zone of the cerebral hemispheres. It is responsible for the regulation of motor movements, and receives information on the body’s ability to perceive its own position in space.
With the help of the spinocerebellum, we can tell whether we stand on a patch of grass or on a concrete street without looking.
Vestibulocerebellum
This functional area of the cerebellum receives sensory information from the vestibular nuclei in the brainstem. In this way, it regulates balance, and coordinates the eye movement with the rotation of the head (a visual fixation on a target, for example).
What Types of Cells Does the Cerebellum Consist Of?
The cerebellar cortex consists of several distinct types of nerve cells and neuronal fibers:
- Purkinje cells – Flask-like neurons located in the cerebellar cortex of the brain, with massive outward-directed dendrites.
- Basket cells – The most common, large-bodied cells with 4-10 dendrites spreading in all cortical layers.
- Stellate cells – Star-shaped neurons due to the form made by the dendrites which spread from them.
- Golgi cells – Interneurons, i.e. cells responsible for the transport of protein and building of liposomes.
- Granular cells – The only excitatory neurons present in the cerebellar cortex with four to five dendrites ending in an enlargement (a dendritic claw), packed into a thick granular layer at its bottom.
- Mossy fibers – They transport the sensory information from the pons to the other structures of the cortex for further processing.
- Parallel fibers – They transmit the electrical impulses from the neurons to the basket cells and the stellate cells, which further pass the sensory information to the Purkinje cells.
- Climbing fibers – These structures are located on the terminals of the axons. They perform a central role in motor movements by modifying the strength of synapses of the Purkinje cell dendrites.
What Is the Construction of the Cerebellum’s Vasculature System?
The cerebellum receives supplies through blood passing through the vascular system created by the following pairs of arteries:
- Superior cerebellar artery (SCA) – It arises from the top of the basilar artery, and supplies the superior surface of the cerebellum and parts of the midbrain.
- Anterior inferior cerebellar artery (AICA) – It arises at the junction of the medulla oblongata and the pons. It also supplies blood to the cerebellum as a branch of the basilar artery.
- Posterior inferior cerebellar artery (PICA) – Terminal branch of the basilar artery which arises from the vertebral artery. It supplies the occipital, temporal lobes, and visual areas of the cerebral cortex.
What Happens If the Cerebellum Is Dysfunctional?
A dysfunctional cerebellum can lead to various medical conditions (including personality changes), such as:
- Ataxia – An inability to coordinate balance, gait, extremity, and eye movements.
- Asynergia – loss of movement coordination, which can appear as clumsiness or abnormal movements.
- Dysmetria – An inability to perform accurate movements. This is a type of Ataxia which results in problems with reaching out and accurately touching a targeted object.
- Dysrhythmia – Incoordination of movement, as well as an abnormal rhythm and timing of movements of the extremities.
- Nystagmus (coarse) – A damage to the flocculonodular lobe can result in nystagmus. It’s an abnormal, rhythmic, and rapid movement of the eyes.
- Scanning speech – A motor speech disorder caused by a neurological injury to the cerebellum, resulting in the person breaking up spoken words into separate syllables.
- Intention tremor – A slow shaking of the extremities which increases when there is a voluntary effort to move them.
- Hypotonia – A reduction of the normal resting tension of the muscles, which can lead to a ‘hanging’ appearance of the extremities.
- Schizophrenia – A mental disorder caused by atrophy of the cerebellar vermis. The individual suffers from illusion and withdrawal from reality, inappropriate actions and feelings, as well as delusion.
- Adiadochokinesia – An inability to perform coordinated, alternated movements, such as rotating a closed fist.
Cerebellar disorders are typically characterized by impaired muscle coordination, frequent stumbling, uncontrolled or repetitive eye movements, slurred speech, vocal changes, and headaches.
To Sum Up
The cerebellum is the part of the cerebral cortex which integrates sensory and other inputs from many regions of both the brain and spinal cord.
It coordinates motor movements and regulates their timing, it coordinates muscle tone, regulates balance, coordinates eye movements with the rotation of the head, and is responsible for motor planning before any movement is performed.
The cerebellum is often labeled as the ‘little brain’, because it has many similar functions and anatomy with the bigger (and main) part of the brain, i.e. the cerebrum.
This small, yet powerful part of the brain also plays an enormous role in our everyday life, especially concerning physical movements like walking, exercising, maintaining our personal hygiene, reaching for objects, eating, etc.
A possible injury or damage to the cerebellum can lead to various medical conditions and serious disorders and impairments of its primary functions: an inability to plan movements, lack of verbal fluency, problems with visual-spatial organization, memory, and speech.
Fun Facts
Did you know?
1. Even though the cerebellum is considered to be the ‘little brain’, as it takes up only 10% of the brain’s volume, it’s made up of almost 50% of the brain’s neurons which gives it a great role in the central nervous system.
2. The cerebellum is one of the oldest parts of the human brain, being developed in the course of the evolutionary process which commenced over 400 million years ago.
3. The posterior lobe of the cerebellum is linked to happiness, as it regulates and controls the subjective experience of pleasant feelings in response to happiness-evoking stimuli.
4. The flocculonodular lobe’s function is exceptionally important for ballet dancers. Namely, during the performance of pirouettes, it helps them coordinate their gaze with the repetitive and forceful rotation of the head during that movement. By performing this function, the flocculonodular lobe of the cerebellum spares them from dizziness.
5. After an inflicted injury to the cerebellum, its endogenous repair mechanisms can heal the brain and prevent behavioral motor deficits.
6. Proper and healthy nutrition for a healthy and functional cerebellum includes protein and fats, as well as complex carbohydrates (unsweetened fruits, starchy vegetables, legumes, rice, and pasta).
7. A medical condition caused by a dysfunctional cerebellum, called asynergia, can make a person clumsy.
8. The cerebellum is responsible for the richness of our emotional life by helping us fine-tune our deepest thoughts and emotions.
9. This little portion of the brain plays a big role in our everyday life, especially in circumstances where strength and perseverance are required the most. Namely, the proper function of the cerebellum is of vital importance for our excellent athletic performance.
10. Exercising improves the blood flow to all regions of the brain, thus making them stronger and more functional.