Types of Neurons

Last update: Nov 1st, 2022

Nerve cells are functionally classified as sensory neurons, motor neurons, or interneurons.

Sensory neurons (afferent neurons) are unipolar, bipolar, or multipolar shaped cells that conduct action potentials toward or into the central nervous system.

An image showing the basic structures of the neuron, the action potential moving through the axon, the interneuron and fascilce are labeled

They carry somatic nervous system signals from the skin, joints, skeletal muscles, sensory organs (eyes, ears, mouth, and nose). They also carry autonomic nerous system signals from the visceral organs (heart, lungs, vessels, etc).
In comparison, motor neurons (efferent neurons; lower motor neurons) are multipolar shaped cells that conduct action potentials out of the central nervous system.

Learn the anatomy of the nervous system faster and more efficiently with this step-by-step guide full of interactive quizzes and diagrams.

Their cell bodies and dendrites are located in the central nervous system and their axons run inside the nerves to the peripheral organs.
Interneurons(internuncial or association neurons) are the billions of cells that form much of the central nervous system and link the sensory and motor neurons.

After receiving input from the sensory neurons, the interneurons perform many complex tasks inside the CNS.
First, they integrate, image, and interpret, the sensory information.
Next, they form judgments and make needed decisions.
Finally, they plan and initiate appropriate response behaviors, which they transfer to the motor neurons.

Let’s take a another look at the functional classes of neurons using an illustration that is more anatomically correct.
Sensory neurons inside the nerves conduct electro-chemical signals (action potentials) from peripheral receptors to the CNS.