Summary
Sensory neurons carry information to the CNS; motor neurons carry commands to muscles and glands.
In depth
Afferent neurons carry impulses toward the CNS and efferent away from it. Cell bodies of sensory neurons lie in dorsal root ganglia. Interneurons connect them within the CNS and are the majority in the brain.
Sensory neurons are pseudounipolar; motor neurons are multipolar. Upper motor neurons begin in the cortex; lower motor neurons project to muscles.
Example: ALS affects both.
Sensory neurons are mostly pseudounipolar with the cell body in a dorsal root ganglion, and fibres classified by diameter and speed: Aalpha (up to 120 m/s, proprioception), Abeta (touch), Adelta (fast pain, temperature) and C (slow pain, unmyelinated, about 1 m/s). Motor neurons: upper motor neurons from the cortex descend in corticospinal tracts to synapse with lower motor neurons in the spinal cord or brainstem, which innervate muscles. A motor unit is one motor neuron and the fibres it controls, from a few fibres in the eye to thousands in leg muscles.
Disease: ALS (motor neuron disease) destroys both types, polio the lower motor neurons, and peripheral neuropathy (diabetes) damages sensory neurons. Damaged lower motor neurons cause flaccid paralysis, and upper motor neuron lesions cause spasticity.
Remember: afferent means arriving at the CNS, efferent exiting.
Frequently asked questions
What is Sensory and Motor Neurons?
Sensory neurons carry information to the CNS; motor neurons carry commands to muscles and glands.
Which area of biology covers Sensory and Motor Neurons, and how advanced is it?
Sensory and Motor Neurons is one of the 54 topics in Neuroscience. It is rated Beginner, so it suits learners who are starting out in biology. Related topics in this area include Neuron, Spinal Cord Functions, Brain Regions.
Can you give an example of Sensory and Motor Neurons?
Damage to motor neurons causes paralysis; damage to sensory ones causes numbness.
What should I learn before Sensory and Motor Neurons?
Sensory and Motor Neurons is a Beginner topic, so no earlier topic is required. Other Beginner topics in Neuroscience that pair well with it include Nervous System, Neuron, Central and Peripheral Nervous Systems.
What topics are related to Sensory and Motor Neurons?
The closest topics to Sensory and Motor Neurons are Neuron, Spinal Cord Functions, Brain Regions, Central and Peripheral Nervous Systems. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Sensory and Motor Neurons?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Sensory and Motor Neurons. To practise the whole of Neuroscience, use the Neuroscience quiz.
How is Sensory and Motor Neurons different from Neuron?
Sensory and Motor Neurons: Sensory neurons carry information to the CNS; motor neurons carry commands to muscles and glands. Neuron: A nerve cell with dendrites, a cell body and an axon that transmits electrical signals. Read both side by side and note what each one explains.
How should I study Sensory and Motor Neurons step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Neuron and explain the difference aloud. Finally, take the Neuroscience quiz and come back to this page for any question you miss.