Central nervous system

From WikiMD's Wellness Encyclopedia

The Central Nervous System (CNS) is an intricate network of neural tissues that control the activities of the body. Primarily located within the dorsal body cavity, it is divided into two major components: the brain and the spinal cord. The brain resides in the skull, enclosed by the cranium, while the spinal cord, which extends from the brain, is encased within the protective column of vertebral bones.


The CNS is a critical coordinating center for physiological processes, orchestrating a variety of functions that range from motor control to cognitive activities. At its uppermost end, the spinal cord meets the brain at the foramen magnum, a large opening at the base of the skull.

Surrounding the CNS are protective layers known as the meninges, consisting of three layers: the durable dura mater, the web-like arachnoid mater, and the delicate pia mater that directly covers the brain and spinal cord. These meningeal layers, along with the cerebrospinal fluid, cushion the brain and spinal cord from impact, provide a basic immune defense, and facilitate the exchange of nutrients and waste.

Components of the CNS

The CNS can be broken down into the following parts:

  • Brain: The command center of the CNS, comprised of billions of interconnected neurons and glia, organized into specialized regions responsible for processing sensory information, regulating bodily functions, and facilitating cognition and emotional responses.
  • Spinal Cord: A long, slender column of nervous tissue that transmits neural signals between the brain and the rest of the body, and is a center for coordinating reflexes.

Function and Purpose of the CNS

The CNS has several key roles:

  • Signal Transmission: Neurons convey electrical and chemical signals throughout the body, regulating functions such as movement, sensation, and autonomic responses to the environment.
  • Processing and Integration: The CNS interprets sensory data, formulating appropriate responses to stimuli.
  • Cognition and Emotion: Higher-order functions, such as thinking, memory, and emotion, are governed by the CNS.

Neurons: The Basic Unit

At the core of the CNS lies the neuron, which serves as the primary functional unit. Notable features include:

  • Cell Body (Soma): Contains the nucleus and is the site of vital cellular activities.
  • Axons: Long processes that transmit signals away from the cell body to other neurons or effector cells.
  • Dendrites: Branch-like structures that receive signals from other neurons.
  • Synapses: Specialized junctions where neurons communicate with each other through neurotransmitters.

Nerve fibers (axons) bundled together form nerves, which traverse the body, allowing for intricate communication networks.

Glossary of Terms

  • Axon - The long threadlike part of a nerve cell along which impulses are conducted from the cell body to other cells.
  • Dendrite - The branching process of a neuron that conducts impulses toward the cell body.
  • Glia - Non-neuronal cells in the CNS that provide support and protection for neurons.
  • Meninges - The three membranes that envelop the brain and spinal cord.
  • Cerebrospinal fluid - The clear liquid that surrounds and cushions the brain and spinal cord.
  • Synapse - The junction between two nerve cells, consisting of a minute gap across which impulses pass by diffusion of a neurotransmitter.
  • Neural networks - Interconnected neuron cells that process and transmit information in the nervous system.
  • Reflex - An involuntary response to a stimulus controlled by the spinal cord.
  • Soma (also known as Cell Body) - The bulbous end of a neuron, containing the cell nucleus.
  • Neurotransmitter - Chemical substances that transmit signals across a synapse from one neuron to another.
  • Foramen magnum - The hole in the base of the skull through which the spinal cord passes.
Central nervous system Resources


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Contributors: Prab R. Tumpati, MD