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Anatomy of the Central Nervous System

Central Nervous System Overview

The central nervous system consists of the brain and spinal cord (see Multimedia File 1).

  • The brain plays a central role in the control of most bodily functions, including awareness, movements, sensations, thoughts, speech, and memory. Some reflex movements can occur via spinal cord pathways without the participation of brain structures. 


  • The spinal cord is connected to a section of the brain called the brainstem and runs through the spinal canal. Cranial nerves exit the brainstem. Nerve roots exit the spinal cord to both sides of the body. The spinal cord carries signals (messages) back and forth between the brain and the peripheral nerves.

Cerebrospinal fluid surrounds the brain and the spinal cord and also circulates within the cavities (called ventricles) of the central nervous system. The leptomeninges surround the brain and the spinal cord. The cerebrospinal fluid circulates between 2 meningeal layers called the pia matter and the arachnoid (or pia-arachnoid membranes). The outer, thicker layer serves the role of a protective shield and is called the dura matter.

The basic unit of the central nervous system is the neuron (nerve cell). Billions of neurons allow the different parts of the body to communicate with each other via the brain and the spinal cord. A fatty material called myelin coats nerve cells to insulate them and to allow nerves to communicate quickly.



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Anatomy of the Central Nervous System

What is the central nervous system?

The central nervous system is the part of the nervous system made up of the brain and spinal cord.


The central nervous system

  • The brain controls most bodily functions, such as voluntary movements, perception of sensations, memory, awareness, and thoughts.  

    • The cerebrum controls voluntary actions, speech, thought, and memory. The cortex, also called gray matter, is the outer part of the cerebrum and is made of neurons (nerve cells). Most of the brain's information processing is done in the cortex. 
    • The brain is divided into 2 halves: the right hemisphere and the left hemisphere. These hemispheres lie on a central structure called the thalamus, which relays information between the peripheral input from the senses and the brain. Other central structures include the hypothalamus, which regulates automatic functions such as appetite and thirst, and the pitui...

Read the Myelin and the Central Nervous System article »



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