2014 Somatosensation

Classification of somatosensory nerve fibres

Somatosensory nerve fibres can be divided into several subcategories based on their conduction velocity (which is determined by their diameter and degree of myelination).

This classification system is important for understanding pain and the mechanism of action of local anaesthetics.
Critical Fact

Conduction Velocity Classification
Fibre Type
Axon Diameter (microns)
Conduction Velocity (m/s)
Modalities
Myelinated Fibres
14.0
25
mechanoreception
11.0
17

mechanoreception, cold, fast pain

Unmyelinated Fibres
C
2.5
0.4-0.5

mechanoreception, thermoreception, slow pain

* for reference, B fibres ---- myelinated fibres found in autonomic nerves that are the same diameter as C fibres --- conduct at least 10X faster (3-15 m/s) than C fibres

Email: Dr. Janet Fitzakerley | ©2014 University of Minnesota Medical School Duluth | Last modified: 5-feb-14 10:28 PM