The brain and spinal cord control and coordinate most functions of the mind and body. The brain is connected to the spinal cord, controls the nervous system, and regulates feelings, thoughts, consciousness, and volition, as well as controlling physical activities.
The brain is made up of a reservoir of nerve tissue and fiber called neuroglia, which nourishes around 100 billion nerve cells. It is composed of many layers of cells and takes up 40 percent of the total volume of nerve tissue. The brain has four cavities, each with its own purpose and level of importance. Yet each part of the brain relies on the other parts and they must work together in order for the brain to function properly.
The largest part of the brain is called the cerebrum which is in charge of consciousness. The cerebrum is divided into two halves, a left and right hemisphere or simply the left and right brain. The two halves are connected by large amounts of nerve fibers which allow communication to pass between the two brains. It is believed that the left and right hemispheres both have different abilities. One side controls motor abilities while the other side controls sensory. Both sides rely on each other yet each side has a different process.
An interesting and important factor is that the left and right hemispheres control the opposite side of the body. For example, whatever a person sees with their left eye, the right hemisphere gathers the information and processes it. Whatever a person sees with their right eye, the left hemisphere takes control and, likewise, will gather the information and process what is seen. Yet each hemisphere is accountable for different types of thinking.
Most people are well-defined in their own style of thinking, having a preference for either the left brain or right brain function. Few people are whole-brained and use both sides of the brain equally. However, the majority of people use the left side of the brain most often.