A free nerve ending
) is an unspecialized, afferent nerve
ending, meaning it brings information from the body's periphery to the brain. They function as cutaneous receptors
and are essentially used by vertebrates
to detect pain
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 penetrate the epidermis
and end in the stratum granulosum
Free nerve ending have different rate of adaptation, stimulus modalities
and fiber types
Rate of adaption
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
. 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.
- MacIver M, Tanelian D (1993). "Free nerve ending terminal morphology is fiber type specific for A delta and C fibers innervating rabbit corneal epithelium". J Neurophysiol 69 (5): 1779–83.
- Nociception: Transduction From the University of Utah.
- Hada R (1990). "[Difference in responses of free nerve endings and Ruffini-type endings innervating the cat mandibular periosteum to square wave pressure stimuli, ramp mechanical stimuli and triangular vibrations]". Shikwa Gakuho 90 (2): 161–80.
- Textbook in Medical Physiology And Pathophysiology: Essentials and clinical problems. Copenhagen Medical Publishers. 1999 - 2000
- Cleland C, Hayward L, Rymer W (1990). "Neural mechanisms underlying the clasp-knife reflex in the cat. II. Stretch-sensitive muscular-free nerve endings". J Neurophysiol 64 (4): 1319–30.
- Somatosensory System from Dr. Daley of North Carolina Wesleyan College.