2023-09-01 by Khushi Goel
Why do our left side of the brain control the right side of our body?
Do you know which organ determines your right- or left-handedness? Yes, it is the ‘Brain’ - the master controller of the human body. The brain is a large complex organ with many sub-parts. It can be divided into the cerebrum (front of the brain), Brainstem (middle of the brain) and the cerebellum (back of the brain). The cerebrum is further divided into the left and right cerebral hemispheres.
Some areas of these cerebellum hemispheres control muscle activity. The cerebellum Neurons (special brain cells) send messages to the brainstem and spinal cord, where they are connected with motor neurons. Motor neurons are a special type of neuron that run throughout the body and allow muscle movements. These motor neuron tracts are criss-crossed inside the human brain such that the neural tracts running in the left side of the body are linked with the right cerebral hemisphere and vice versa. Imagine it like braiding, where you criss-cross two locks of hair by moving them on opposite sides.
This criss-crossed pattern of neurons inside the brain is called ‘decussation’. Scientists have been debating on “why do the tracts cross in the human nervous system” for years. But we do not have a concrete answer yet. A few scientists believe that criss-crossing happened because of the complex three-dimensional structure of the human body and thereby has evolutionary significance. Some scientists have tried to explain this phenomenon using geometrical references. Would you like to know how? Tell us in the comments below and we’ll create a separate post to quench your curiosity.
References:
- https://neuroscience.stanford.edu/news/ask-neuroscientist-why-does-nervous-system-decussate
- https://www.quantamagazine.org/why-the-brains-connections-to-the-body-are-crisscrossed-20230419/
- https://pubmed.ncbi.nlm.nih.gov/24040928/
- https://my-ms.org/anatomy_brain_part1.htm#:~:text=Some%20areas%20of%20the%20cerebral,roots%20in%20the%20spinal%20cord.
- https://www.aans.org/en/Patients/Neurosurgical-Conditions-and-Treatments/Anatomy-of-the-Brain#:~:text=The%20brain%20is%20housed%20inside,the%20brain%20and%20spinal%20cord.