Expert: John Locke - 5/29/2008

Question
The right cerebrum controls the left part of the body and Vice versa why?  

Answer
Thanks for using AllExperts, Nitesh.

It is not exactly true that the left side of the brain controls the right side of the body and vice versa. Many brain functions are lateralized in humans (that is, segregated to the right or left hemispheres), but the truth is not so simple as a right side/left side division: language processing and mathematical logic are controlled by the left hemisphere, while holistic reasoning and artistic ability are controlled by the right hemisphere. However, many other brain functions--emotional responses and sound localization, to name two--are controlled by both hemispheres together.

Perhaps the simplest explanation for this phenomenon is that the brain's anatomy is closer to two connected halves rather than a single whole. The right and left sides of the brain are anatomically distinct, and joined in the middle by the bundle of neurons called the corpus callosum. When you add the fact that the two hemispheres are not mirror images of each other, this virtually guarantees that some functions will be lateralized. Each half of the brain has some unique parts not represented in the other half (these are the lateralized functions), while each half also contains parts mirrored in the other half--these functions will be bilaterally controlled. If you're looking for specifics, the lateral sulcus is longer in the left hemisphere than in the right, meaning that the distribution of neurons must be different from left side to right side.

Perhaps the most accurate generalization about brain function is this: For specific parts of the body, the left side of the brain controls the right side of the body and v.v.

If you're curious, an overview of this question can be found here:

http://faculty.washington.edu/chudler/split.html