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Raphespinal tract

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Raphespinal tract
Details
Identifiers
Latintractus raphespinales
Anatomical terminology

The raphespinal tract is a descending spinal cord tract located in the medulla oblongata.[1] It consists of two tracts an anterior raphespinal tract, and a lateral raphespinal tract that mainly descend in the lateral funiculus.[2][3][4] Fibers descend in the ventral portion of the lateral funiculus, mainly bilaterally to terminate in laminae I, II, and IV.[1]

The tract emerges from three of the raphe nuclei, the magnus, obscurus, and pallidus.[1] The fibers of the raphespinal tract are mainly serotonergic. When raphe nuclei are stimulated they release serotonin which modulates the transmission of pain.[1][2]

Pathways

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Pain pathways converging upon the raphe nuclei to modulate pain via the raphespinal tract include:

Function

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Electrical stimulation of either the periaqueductal gray or (its downstream target) nucleus raphe magnus induces profund analgesia; this effect can be abolished both by transection of the raphespinal tract as well as by opioid receptor antagonists (evidencing one of the mechanisms by which opioid bring about pain relief). An electrical stimulator implant of the periaqueductal gray can be used clinically for pain management, evoking instantaneous pain relief upon activation.[2]

The raphespinal tract appears to also be involved in modulating motor activity as serotonin increases the excitability of motor neurons - serotonin-blocking medications can alleviate spasticity caused by damage to the motor pathways.[2]

See also

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References

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  1. ^ a b c d Tan, Sheryl; Faull, Richard L. M.; Curtis, Maurice A. (April 2023). "The tracts, cytoarchitecture, and neurochemistry of the spinal cord". The Anatomical Record. 306 (4): 777–819. doi:10.1002/ar.25079.
  2. ^ a b c d e Kiernan, John A.; Rajakumar, Nagalingam (2013). Barr's The Human Nervous System: An Anatomical Viewpoint (10th ed.). Philadelphia: Wolters Kluwer Lippincott Williams & Wilkins. pp. 154, 291–293. ISBN 978-1-4511-7327-7.
  3. ^ Donkelaar, Hans J. ten; Kachlík, David; Tubbs, R. Shane. An Illustrated Terminologia Neuroanatomica: A Concise Encyclopedia of Human Neuroanatomy. Springer. p. 418. ISBN 978-3-319-64789-0.
  4. ^ "lateral raphespinal tract".
  5. ^ a b c d Patestas, Maria A.; Gartner, Leslie P. (2016). A Textbook of Neuroanatomy (2nd ed.). Hoboken, New Jersey: Wiley-Blackwell. pp. 224–225, 310–311. ISBN 978-1-118-67746-9.