The brain completely controls the body; it is responsible for the thought and actions that produced this article. The brain is responsible for thought, emotion, perception, memory, learning, movement and the coordinated regulation of the entire body. Nerves send information from limbs and organs to the brain and the brain sends messages through these nerves back to various parts of the body.
The four main parts of the brain are the cerebrum, cerebellum, brain stem and limbic system. The cerebrum makes up most of the brain, basically the entire grey part on the top. Beneath that is the cerebellum, which is small and shaped like a ball. Adjacent to the cerebellum is the brain stem, which extends from the center of the brain to the spine. Within the cerebrum is the limbic system.
The cerebrum exists for thought and action. The frontal lobe is used for reasoning, planning, movement, emotions and problem-solving. The parietal lobe, found at the top of the brain, is also used for movement, perception and recognition. The occipital lobe at the back is used for visual processing alone. At the bottom of the cerebrum is the temporal lobe, which is used for hearing, memory and speaking.
The limbic system, found within the cerebrum, is called the emotional part of the brain. The thalamus directs sensory perceptions; the hypothalamus controls emotions, thirst, hunger and equilibrium; the amygdala regulates memory, emotion and fear; and the hippocampus is used for memory and learning.
The cerebellum is considered one of the older parts of the brain, meaning that on an evolutionary scale it was developed sooner than the cerebrum. The cerebellum controls movement, gait, balance and muscle tone. The importance of the cerebellum is made clear when someone receives damage to this part of the brain---such an injury often leads to uncoordinated movement and slowness.
The brain stem is in charge of basic life functions. The human brain stem is similar to the brain stems of other species. The midbrain controls motor functions and relays sensory information from sensory organs. The pons control sensory analysis and motor control. The medulla oblongata regulates basic functions like heart beat and breathing.