The nervous system is comprised of three primary structures: the brain, spinal cord and nerves. Together, these systems control all aspects of the body from simple movements to solving complex calculations. The spinal cord and nerves play vital roles in receiving, sending and sorting signals from the environment to the body, but the brain is the master controller. The brain can be divided into several sections and structures that each perform a specific function, but they all work together to provide the body and mind with the correct information to function properly.
Cerebrum
The cerebrum lies in the forebrain and is divided into two cerebral hemispheres, covered by the cerebral cortex, or outer layering of the brain. The cerebrum is often referred to as the master controller of the brain and is involved in all aspects of cognitive thinking. The cerebral cortex is divided into distinct lobes based on specific functions. Sensory information is managed by the parietal lobe, such as touch or pain perception. The occipital lobe receives and interprets visual information while the temporal lobe handles auditory information. The frontal lobe performs executive functions, such as goal-setting, planning, reasoning, judgment, motor skills and storing long-term memories.
Limbic System
The limbic system lies below the cerebrum and is composed of the hippocampus, amygdala, thalamus and hypothalamus. It primarily functions in memory, emotion and motivation. The hippocampus is involved in memory formation and retrieval. It also plays a role in spatial memory, which is the memory required to navigate around a person's hometown, for example. The amygdala plays a role in emotions, such as aggression or fear, and along with the hippocampus, is involved in memory.
Thalamus and Hypothalamus
These two brain structures of the limbic system play pivotal roles in a variety of brain and bodily functions. The thalamus functions as a switchboard for incoming sensory information, relaying that information to higher order brain centers.
The hypothalamus functions in the control of body homeostasis as well as hormone secretion, emotion and motivation. It is vital in regulating hunger, thirst, sleep, fluid balance, blood pressure and body temperature. In linking the nervous system to the endocrine system, the hypothalamus regulates the secretion of the hormones from the pituitary gland, such as vasopressin or oxytocin.
Midbrain
The midbrain is the smallest division of the brain, but it is important for relaying information to other areas of the brain. It contains the reticular formation, which acts as a filtering system for incoming stimuli. The groups of fibers that compose the reticular formation carry information about arousal and sleep to other areas of the brain. The reticular formation blocks or allows incoming information from external stimuli from reaching higher brain centers, and thus consciousness. The reticular formation is important in an individual's abilities to habituate to repetitive stimuli, such as being able to sleep with the television on, but waking upon the loud burst of sound from an alarm clock.
Hindbrain
The hindbrain is the most primal brain structure located at the base of the brain and composed of the cerebellum and brain stem. It functions to coordinate motor movement as well as supports basic life functions. The cerebellum is the motor coordination center of the brain providing the much needed timing and coordination involved in movement.
The brain stem is composed of the pons and medulla oblongata, which support vital life functions. The medulla oblongata provides control of heart rate and breathing. The pons relay information between higher and lower levels of the nervous system and function in sleep and arousal as well as play a role in controlling vital functions, particularly respiration.
