The human brain is the most complex and wonderful discovery the man ever made. Inside the brain, several divisions work together every second to deliver the experience what we are enjoying even now.
The Cerebrum and Cerebellum are one such magnificent parts. Both have similar names but with distinct differences, and when working together produce miracles. The central nervous system in human beings is made up of four parts namely, cerebrum, cerebellum, brain stem and spinal cord.
Cerebellum vs Cerebrum
The main difference between cerebrum and cerebellum is that the former is related to planning and executing a variety of functions while the latter is related to the coordination of the activities, especially the motor activities.
The cerebrum is the largest part of the central nervous system with more complex functions.
Comparison Table Between Cerebellum and Cerebrum (in Tabular Form)
| Parameter of Comparison | Cerebrum | Cerebellum |
|---|---|---|
| Size | Largest of the central nervous system | Smaller than cerebrum |
| Functions | Sensory, motor and higher mental functions | Motor coordination, posture maintenance, and balance |
| Parts | 2 cerebral hemispheres with 4 lobes on each hemisphere. | 2 cerebellar hemispheres that are connected by peduncles to the brain stem. |
| Forming which component of Brain | Forebrain | Hindbrain |
| Fibers connecting two side hemispheres | Corpus callosum | Vermis |
| Association with memory | Associated with memory | Not always associated with memory. |
| Role in motor activities | Planning and initiation of motor movements | Coordination of motor activities |
| Language skills | It decides what to talk about and initiates the language and is also responsible for the comprehension of the language. | Coordinates the speech articulation |
| Vision | Records and comprehends the visual stimulus | Coordination of eye movements in response to a sensory stimulus. |
What is Cerebellum?
Cerebrum, also known as Telencephalon, is the largest part of the human brain, comprising almost 2/3 of the cranial vault of the skull. It is divided into two hemispheres, viz right and left hemispheres. Each of these hemispheres controls the body on the opposite side.
The foresaid hemispherical division of the cerebrum is made up with the help of the median longitudinal fissure. Each hemisphere is composed of 4 lobes namely, Frontal, parietal, temporal and occipital. Each of these lobes is primarily associated with an individual group of functions.
And also each side of the hemisphere is related to a particular set of abilities. For instance, the person who has more right-brain activities will be more efficient in creativity, spatial skills, music, and other artistic skills.
Whereas, the person with left-brain dominance, will be more efficient with logical reasoning, arithmetic operations, writing. The cerebrum is divided based on the nature of the cells it is made of into, grey matter and white matter. The grey matter represents the cell bodies of a variety of neurons while the white matter represents the extensions of the cell bodies, which we call axons.
Any activity that is executed by the cerebrum starts from the grey matter and transmitted to the effector’s sites by the white matter.
The cerebral hemisphere on external appearance reveals elevations and depressions on the surfaces which are called gyri and sulci respectively.
There are 3 main sulci and 3 main gyri one should know about,
Central, lateral and lunate sulci are those which form the boundaries between the lobes of the cerebral hemispheres. Superior temporal, precentral and postcentral gyri are those which separates the cortex based on functional significance.
The nutrition to these regions is provided by the arteries such as anterior, middle and posterior cerebral arteries. Occlusion in these arteries leads to the most commonly seen condition which we all know as Stroke or cerebrovascular accident. The effect of the occlusion or damage varies with different arteries being affected.
What is Cerebrum?
The cerebellum is the second largest part of the brain that is placed on the posterior cranial fossa inside the cranial vault. Though the initiation of all the motor movements in the cerebrum requires the primary sensory data from the cerebellum, the cerebellum cannot independently initiate a motor movement.
The main functions of the cerebellum are, coordination of motor movements, maintaining posture, gait, and balance.
The dura matter( layer of the meninges) layer that covers the cerebellum in its locations is called tentorium cerebelli. This cerebellum is divided into two-sided hemispheres and connected my vermis which is a medial eminence. The cerebellum is connected with the brain stem with help of superior, middle and inferior cerebellar peduncles, through which the input and outputs to and from the cerebellum pass.
Cerebellum has two parts when classified based on the cells as gray matter and white matter. The grey matter containing the cell bodies is further divided into 3 layers, outer molecular, middle- Purkinje and internal granular layer.
The types of cells that make up the cerebellum are Stellate, Basket, Golgi, Purkinje, Granular and unipolar Brush cells.
These different parts play different roles in different movements, for instance, the area of the vermis cortex is important in coordinating the movements of the trunk of the human body, while the intermediate zone of the cerebellar hemisphere deals with the movements in the distal extremities.
The conscious assessment and coordination of movements all over the body are mediated by the lateral area of the cerebellar hemispheres. The blood is supplied to the cerebellum through 3 main arteries namely, superior, anterior and posterior cerebellar arteries.
Main Differences Between Cerebellum and Cerebrum
- The cerebrum is the largest part of the brain. The cerebellum is the second largest part of the brain.
- Cerebrum initiates the motor movements. The cerebellum coordinates the motor movements.
- Cerebral hemispheres are connected by the corpus callosum. Cerebellar hemispheres are connected by vermis.
- The cerebrum is associated with higher mental functions in addition to the motor and sensory functions. The cerebellum is associated with the coordination of motor movements, maintaining posture, gait, and balance.
- Cerebrum when endured damage will lead to alteration in consciousness and personality of an individual in addition to motor defects. Cerebellum when suffered damage will lead to motor defects only.
- The cerebrum is supplied by anterior, middle and posterior cerebral arteries. The cerebellum is supplied by Superior, Anterior and Posterior cerebellar arteries.
Conclusion
Though cerebrum and cerebellum do different functions internally, coordinated activity of these two structures is essential for the proper initiation and completion of a smooth motor activity. Without one, the other cannot function normally.
The thorough understanding of these differences will be of immense significance in times of life-saving diagnosis by healthcare professionals. The importance of these two structures is evident in their location, which is well protected by a number of factors and agents.
References
- https://n.neurology.org/content/63/6/989.short
- https://jnnp.bmj.com/content/80/2/182.short