A delta fibers, or Aδ fibers, are a type of sensory fiber. They are associated with cold and pressure, and as nociceptors they convey fast pain information.
They are much faster than the C fibers because they are myelinated, but they are much thinner than other "A" caliber nerve fibers, so they conduct signals more slowly than the other fibers of that class.
They are thin, myelinatedaxons with a moderate conduction velocity, or speed of travel of a nerve signal (2 to 30 m/s). These nerve fibers are associated with acute (sharp) pain and therefore constitute the afferent portion of the reflex arc that results in "pulling away" from noxious stimuli (ie: yanking hand away from hot stove). A certain proportion of Aδ fibers are also associated with sensations of temperature (also known as 'cold receptors' in mammals) and pressure. Slowly-conducting, unmyelinated C fibers, by contrast, carry slow, burning pain.
