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Which structures make up the human nervous system?

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Vintage anatomy chart showing front and back views of the human skeletal system and muscular system, with detailed illustrations of bones and muscles. — human body Vintage anatomy charts of the human body showing the skeletal and muscle systems.

The human nervous system is a complex network that conducts electrochemical stimuli between sensory receptors and the rest of the body. It is primarily organized into two main divisions:1

The Central Nervous System (CNS)

The CNS serves as the body's processing center, responsible for receiving, coordinating, and responding to information. It consists of:2
* Brain: The center of cognition and emotion, encased within the skull.32
* Spinal Cord: A conduit for communication between the brain and the body, also housing circuits for automatic reflexes.2
Both structures are protected by membranes called meninges and cushioned by cerebrospinal fluid.32

The Peripheral Nervous System (PNS)

The PNS includes all neural tracts and structures located outside the brain and spinal cord. It relays sensory signals to the CNS and transmits motor responses to muscles and glands. A key component is the autonomic nervous system, which regulates involuntary bodily functions through the sympathetic, parasympathetic, and enteric divisions.24

At the cellular level, the entire system is composed of neurons—typically featuring a cell body, axon, and dendrites—and support cells known as glia.52