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Group Aβ of the type II sensory fiber is a type of sensory fiber, the second of the two main groups of touch receptors. The responses of different type Aβ fibers to these stimuli can be subdivided based on their adaptation properties, traditionally into rapidly adapting (RA) or slowly adapting (SA) neurons. Type II sensory fibers are slowly-adapting (SA), meaning that even when there is no change in touch, they keep respond to stimuli and fire action potentials. In the body, Type II sensory fibers belong to pseudounipolar neurons. The most notable example are neurons with Merkel cell-neurite complexes on their dendrites (sense static touch) and Ruffini endings (sense stretch on the skin and over-extension inside joints). Under pathological conditions they may become hyper-excitable leading to stimuli that would usually elicit sensations of tactile touch causing pain. These changes are in part induced by PGE2 which is produced by COX1, and type II fibers with free nerve endings are likely to be the subdivision of fibers that carry out this function.
Group Aα of the type II sensory fiber is another type of sensory fiber, which participate in the sensation of body position (proprioception). In each muscle, we have 10-100 tiny muscle-like pockets called muscle spindles. The type II fibers (aka secondary fibers) connect to nuclear chain fibers and static nuclear bag fibers in muscle spindles, but not to dynamic nuclear bag fibers. The typical innervation to muscle spindles consists of one type Ia fiber and 2 type II fibers. The type Ia fiber has "annulospiral" endings around the middle parts of the intrafusal fibers compared to type II fibers that have "flower spray" endings which may be spray shaped or annular, spreading in narrow bands on both sides of the chain or bag fiber. It is thought that the Ia fibers signal the degree of change in muscle movement, and the type II fibers signal the length of the muscle (which is later used for forming the perception of the body in space).
References
- Olson W, Dong P, Fleming M, Luo W (May 1, 2016). "The specification and wiring of mammalian cutaneous low-threshold mechanoreceptors". Wiley Interdisciplinary Reviews: Developmental Biology. 5 (3): 389–404. doi:10.1002/wdev.229. PMC 4864430. PMID 26992078.
- de Moraes ER, Kushmerick C, Naves LA (October 2017). "Morphological and functional diversity of first-order somatosensory neurons". Biophysical Reviews. 9 (5): 847–856. doi:10.1007/s12551-017-0321-3. PMC 5662056. PMID 28889335.
- Sun W, Yang F, Wang Y, Fu H, Yang Y, Li CL, Wang XL, Lin Q, Chen J (February 2017). "Contribution of large-sized primary sensory neuronal sensitization to mechanical allodynia by upregulation of hyperpolarization-activated cyclic nucleotide gated channels via cyclooxygenase 1 cascade". Neuropharmacology. 113 (Pt A): 217–230. doi:10.1016/j.neuropharm.2016.10.012. PMID 27743933. S2CID 20247.
- Arcourt A, Gorham L, Dhandapani R, Prato V, Taberner FJ, Wende H, Gangadharan V, Birchmeier C, Heppenstall PA, Lechner SG (January 2017). "Touch Receptor-Derived Sensory Information Alleviates Acute Pain Signaling and Fine-Tunes Nociceptive Reflex Coordination". Neuron. 93 (1): 179–193. doi:10.1016/j.neuron.2016.11.027. PMID 27989460.
- Niessen MH, Veeger DH, Koppe PA, Konijnenbelt MH, van Dieën J, Janssen TW (February 2008). "Proprioception of the shoulder after stroke". Archives of Physical Medicine and Rehabilitation. 89 (2): 333–8. doi:10.1016/j.apmr.2007.08.157. PMID 18226659.
- Poliak S, Norovich AL, Yamagata M, Sanes JR, Jessell TM (January 2016). "Muscle-type Identity of Proprioceptors Specified by Spatially Restricted Signals from Limb Mesenchyme". Cell. 164 (3): 512–25. doi:10.1016/j.cell.2015.12.049. PMC 4733250. PMID 26824659.
- Mancall, Elliott L; Brock, David G, eds. (2011). "Chapter 2 - Overview of the Microstructure of the Nervous System". Gray's Clinical Neuroanatomy: The Anatomic Basis for Clinical Neuroscience. Elsevier Saunders. pp. 29–30. ISBN 978-1-4160-4705-6.
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This article has multiple issues Please help improve it or discuss these issues on the talk page Learn how and when to remove these messages This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Type II sensory fiber news newspapers books scholar JSTOR November 2017 Learn how and when to remove this message This article may be confusing or unclear to readers In particular the article seems to encompass info about fibers to both muscle spindles and cutaneous receptors but the article begins with mostly info related to muscle spindles then suddenly shifts to info related to cutaneous receptors and the two sets are not compatible for example with introduction about the fiber being non adapting and then later indicating it is rapidly slowly adapting probably needing rewrite in multiple sections with more encompassing introduction Please help clarify the article There might be a discussion about this on the talk page July 2019 Learn how and when to remove this message Learn how and when to remove this message Group Ab of the type II sensory fiber is a type of sensory fiber the second of the two main groups of touch receptors The responses of different type Ab fibers to these stimuli can be subdivided based on their adaptation properties traditionally into rapidly adapting RA or slowly adapting SA neurons Type II sensory fibers are slowly adapting SA meaning that even when there is no change in touch they keep respond to stimuli and fire action potentials In the body Type II sensory fibers belong to pseudounipolar neurons The most notable example are neurons with Merkel cell neurite complexes on their dendrites sense static touch and Ruffini endings sense stretch on the skin and over extension inside joints Under pathological conditions they may become hyper excitable leading to stimuli that would usually elicit sensations of tactile touch causing pain These changes are in part induced by PGE2 which is produced by COX1 and type II fibers with free nerve endings are likely to be the subdivision of fibers that carry out this function Group Aa of the type II sensory fiber is another type of sensory fiber which participate in the sensation of body position proprioception In each muscle we have 10 100 tiny muscle like pockets called muscle spindles The type II fibers aka secondary fibers connect to nuclear chain fibers and static nuclear bag fibers in muscle spindles but not to dynamic nuclear bag fibers The typical innervation to muscle spindles consists of one type Ia fiber and 2 type II fibers The type Ia fiber has annulospiral endings around the middle parts of the intrafusal fibers compared to type II fibers that have flower spray endings which may be spray shaped or annular spreading in narrow bands on both sides of the chain or bag fiber It is thought that the Ia fibers signal the degree of change in muscle movement and the type II fibers signal the length of the muscle which is later used for forming the perception of the body in space ReferencesOlson W Dong P Fleming M Luo W May 1 2016 The specification and wiring of mammalian cutaneous low threshold mechanoreceptors Wiley Interdisciplinary Reviews Developmental Biology 5 3 389 404 doi 10 1002 wdev 229 PMC 4864430 PMID 26992078 de Moraes ER Kushmerick C Naves LA October 2017 Morphological and functional diversity of first order somatosensory neurons Biophysical Reviews 9 5 847 856 doi 10 1007 s12551 017 0321 3 PMC 5662056 PMID 28889335 Sun W Yang F Wang Y Fu H Yang Y Li CL Wang XL Lin Q Chen J February 2017 Contribution of large sized primary sensory neuronal sensitization to mechanical allodynia by upregulation of hyperpolarization activated cyclic nucleotide gated channels via cyclooxygenase 1 cascade Neuropharmacology 113 Pt A 217 230 doi 10 1016 j neuropharm 2016 10 012 PMID 27743933 S2CID 20247 Arcourt A Gorham L Dhandapani R Prato V Taberner FJ Wende H Gangadharan V Birchmeier C Heppenstall PA Lechner SG January 2017 Touch Receptor Derived Sensory Information Alleviates Acute Pain Signaling and Fine Tunes Nociceptive Reflex Coordination Neuron 93 1 179 193 doi 10 1016 j neuron 2016 11 027 PMID 27989460 Niessen MH Veeger DH Koppe PA Konijnenbelt MH van Dieen J Janssen TW February 2008 Proprioception of the shoulder after stroke Archives of Physical Medicine and Rehabilitation 89 2 333 8 doi 10 1016 j apmr 2007 08 157 PMID 18226659 Poliak S Norovich AL Yamagata M Sanes JR Jessell TM January 2016 Muscle type Identity of Proprioceptors Specified by Spatially Restricted Signals from Limb Mesenchyme Cell 164 3 512 25 doi 10 1016 j cell 2015 12 049 PMC 4733250 PMID 26824659 Mancall Elliott L Brock David G eds 2011 Chapter 2 Overview of the Microstructure of the Nervous System Gray s Clinical Neuroanatomy The Anatomic Basis for Clinical Neuroscience Elsevier Saunders pp 29 30 ISBN 978 1 4160 4705 6 This biology article 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