Free nerve ending
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A free nerve ending (FNE) is an unspecialized, afferent nerve ending, meaning it brings information from the body's periphery to the brain. 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. These nerve endings are responsible for detecting temperature, mechanical stimuli (such as pressure), pain (nociception), and information about touch. Some FNEs can also detect stretch stimuli.
The majority of Aδ (A delta) fibers (group III) and C (group IV) fibers end as free nerve endings.
Different types of FNE can be fast-adapting, intermediate, or slow-adapting. Aδ fibres are fast-adapting, while C fibers are slow-adapting.
[edit] External links
- MacIver MB, Tanelian DL. Free nerve ending terminal morphology is fiber type specific for A delta and C fibers innervating rabbit corneal epithelium. J Neurophysiol. 1993 May;69(5):1779-83.
- Gray H. Gray's Anatomy. Online edition. 2000.
- Nociception: Transduction. From the University of Utah.
- Hada R. 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. 1990 Feb;90(2):161-80.
- Textbook in Medical Physiology And Pathophysiology: Essentials and clinical problems. Copenhagen Medical Publishers. 1999 - 2000
- Cleland CL, Hayward L, Rymer WZ. Neural mechanisms underlying the clasp-knife reflex in the cat. II. Stretch-sensitive muscular-free nerve endings. J Neurophysiol. 1990 Oct;64(4):1319-30.
- Somatosensory System from Dr. Daley of North Carolina Wesleyan College.
- Nerve Terminations - CATS program of the University of Vermont College of Medicine.
| Nervous system - Sensory system - Somatosensory system - edit |
|---|
| Spinal pathway: Somatosensory information |
| Medial lemniscus: Touch (Pressure & Vibration) | Proprioception Spinothalamic tract: Pain | Temperature |
| Receptors |
| Touch: Pacinian corpuscles | Meissner's corpuscles | Merkel's discs | Ruffini endings | Free nerve endings | Hair follicle receptors Proprioception: Golgi organ | Muscle spindle (Intrafusal muscle fiber) Pain: Nociceptors Temperature: Thermoreceptors |
