| Free nerve ending | |
|---|---|
| Latin | terminatio neuralis libera |
| Code | TH H3.11.06.0.00002 |
A free nerve ending (FNE) is an unspecialized, afferent nerve ending, meaning it brings information from the body's periphery toward the brain. They function as cutaneous receptors and are essentially used by vertebrates to detect pain.
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Free nerve endings are unencapsulated and have no complex sensory structures, unlike those found in Meissner's or Pacinian corpuscles. They are the most common type of nerve ending, and are most frequently found in the skin. They mostly resemble the fine roots of a plant. They penetrate the epidermis and end in the stratum granulosum. FNE infiltrate the middle layers of skin and surround hair follicles.
Free nerve ending have different rate of adaptation, stimulus modalities and fiber types.
Different types of FNE can be rapidly adapting, intermediate adapting, or slowly adapting. Aδ fibres are fast-adapting, while C fibers are slowly adapting.
Free nerve endings can detect temperature, mechanical stimuli (touch, pressure, stretch) or pain (nociception). Thus, different free nerve endings work as thermoreceptors, cutaneous mechanoreceptors and nociceptors. In other words, they express polymodality.
The majority of Aδ (A delta) fibers (group III) and C (group IV) fibers end as free nerve endings.
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