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How do pain signals travel from injured tissue to the spinal cord?
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pain
Learn how the human body senses pain and reacts to it.
When tissue damage occurs, pain signals are initiated at pain receptors—specialized nerve endings located in the skin and other tissues that respond to mechanical, thermal, or chemical stimuli.1
These signals are transmitted from the tissues to the spinal cord via two primary types of afferent nerve fibers:1
- A delta fibres: These are larger, myelinated fibers that conduct impulses rapidly. They are associated with the initial, sharp, and well-localized sensation of pain.1
- C fibres: These are smaller, unmyelinated fibers that conduct more slowly. They respond to a broader range of stimuli and are responsible for the lingering, poorly localized pain that follows the initial sharp sensation.1
Once these electrical impulses reach the spinal cord, they synapse primarily on neurons within the dorsal horn of the gray matter. This region acts as a critical site for regulating and modulating incoming pain signals before they are transmitted to the brain via ascending tracts, such as the spinothalamic and spinoreticular tracts.12