Generally, the left hemisphere of the brain controls writing, the Mayfield Clinic explains. It also controls speech, comprehension and arithmetic. Moreover, it is dominant in language and hand use in around 92 percent of people.
The Mayfield Clinic elaborates that the cerebral hemispheres are composed of distinct fissures, which divide the brain into lobes. Both the left and right hemispheres have four lobes: the frontal, temporal, occipital and parietal lobe. The lobes are further divided into regions that serve particular functions. They have complex relationships, and they do not function alone. The frontal lobe is responsible for controlling speech, which involves writing and speaking. It also controls personality, behavior and emotions; problem solving, judgment and planning; intelligence, self awareness and concentration, and body movement. The brain’s left hemisphere is referred to as the "dominant" hemisphere. On the other hand, the right hemisphere plays an important role in spatial processing and interpreting visual information.
According to the College of Public Health and Health Professions at the University of Florida, the cerebral hemispheres work together to store memories, make judgments, form thoughts and learn new information. The parietal lobes also play a key role in language and speech, including writing, reading, calculating numbers and doing learned skilled actions. Neurons in the brain are responsible for storing and processing information.