Medical Health Encyclopedia

The Hemispheres. The two hemispheres control higher brain functions, such as memory, learning, decision making, and processing input from the senses. They are each divided into four lobes, which regulate different brain functions:

• Frontal lobe: This is the brain's "gatekeeper." It controls higher motor functions, including speech, and governs concentration, attention, inhibition, judgment, and personality traits.
• Parietal lobe: Processes information from the senses and controls walking, posture, and head and eye movements.
• Occipital lobe: Responsible for interpreting visual input from the eyes.
• Temporal lobe: Responsible for interpreting auditory input from the ears. Also regulates how language is interpreted and retrieves information for memory storage.

The Basal Ganglia. The basal ganglia are clusters of gray matter within each of the lobes. They are important for coordinating voluntary muscle movement, balance, and posture.

The Limbic System. The limbic system is located deep in the cerebrum and controls interpretation of smell, instinctive behavior, emotions, and drives.

Brain Stem

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The brain stem is responsible for all vital functions. It is divided into the following areas, which are responsible for specific functions:

• Medulla: sleep, breathing, heartbeat, digestion, activation of higher forebrain functions
• Pons: sleep, breathing, motor control, activation of higher forebrain functions
• Cerebellum: movement coordination
• Midbrain: walking, posture, head, eye movement
• Hypothalamus: body temperature, appetite, sexual behavior, reproductive hormones
• Thalamus: communication with higher forebrain

The Spinal Cord

The spinal cord extends out of the base of the skull through the vertebrae of the spinal column. It is continuous with the brain. Thirty-one pairs of nerves extend from the sides of the spinal cord to other parts of the body (the peripheral nervous system).

The Meninges and Cerebrospinal Fluid

The meninges are three membranes that enclose the brain and spinal cord. They contain cerebrospinal fluid, which protects the central nervous system from pressure and injury.