Hypothalamospinal tract
| Hypothalamospinal tract | |
|---|---|
| Details | |
| Identifiers | |
| Latin | tractus hypothalamospinalis |
| TA98 | A14.1.05.329 |
| TA2 | 6098 |
| FMA | 77482 |
| Anatomical terminology | |
The hypothalamospinal tract is an unmyelinated[1] non-decussated[2] descending nerve tract that arises in the hypothalamus and projects to the brainstem and spinal cord to synapse with pre-ganglionic autonomic (both sympathetic and parasympathetic) neurons.
The direct autonomic projections of the hypothalamospinal tract represent a minority of the autonomic output of the hypothalamus; most is thought to project to various relay structures.[3]
Anatomy
[edit]Origin
[edit]The tract originates mainly from the paraventricular nucleus of hypothalamus,[4][2] with minor contributions from the dorsomedial, ventromedial, and posterior nuclei of hypothalamus,[4] and lateral hypothalamus.[5][verification needed] The neurons of the hypothalamospinal tract receive direct afferents from the ascending nociceptive sensory spinohypothalamic tract to mediate the autonomic response to painful stimuli.[3]
The tract terminates upon pre-ganglionic autonomic neurons in the brainstem,[3] and spinal segments T1-L3 (sympathetic outflow), and S2-S4 (parasympathetic outflow).[1][3]
Course/relations
[edit]The tract descends through the periaqueductal gray,[5] through the dorsal longitudinal fasciculus,[1] and adjacent to the reticular formation.[5] In the brainstem, it descends in the lateral tegmentum of the midbrain, pons, and medulla oblongata. In the spinal cord, it descends in the dorsolateral quadrant of the lateral funiculus.[6]
Function
[edit]Fibers of the tract terminating at the spinal segment T1 synapse with second-order neurons which in turn synapse in the superior cervical ganglion with third-order neurons which provide sympathetic innervation to the eyelids, pupil, and skin of the face.[7] The hypothalamospinal tract includes fibres by which the hypothalamus projects to the ciliospinal center in the spinal cord, a part of a brain circuit regulating pupillary dilatation as part of the pupillary reflex.[3]
Some axons of the tract contain oxytocin.[1]
Clinical significance
[edit]Lesions of the hypothalamospinal tract above spinal cord level T1 cause ipsilateral Horner's syndrome, which is characterized by a triad of ptosis, miosis, and anhidrosis due to sympathetic denervation of the face.[6]
References
[edit]- ^ a b c d Kiernan, John A.; Rajakumar, Nagalingam (2013). Barr's The Human Nervous System: An Anatomical Viewpoint (10th ed.). Philadelphia: Wolters Kluwer Lippincott Williams & Wilkins. pp. 74, 278. ISBN 978-1-4511-7327-7.
- ^ a b Standring, Susan (2020). Gray's Anatomy: The Anatomical Basis of Clinical Practice (42th ed.). New York: Elsevier. p. 409. ISBN 978-0-7020-7707-4. OCLC 1201341621.
- ^ a b c d e Patestas, Maria A.; Gartner, Leslie P. (2016). A Textbook of Neuroanatomy (2nd ed.). Hoboken, New Jersey: Wiley-Blackwell. pp. 204, 367, 450, 452. ISBN 978-1-118-67746-9.
- ^ a b Patestas, Maria A.; Gartner, Leslie P. (2016). A Textbook of Neuroanatomy (2nd ed.). Hoboken, New Jersey: Wiley-Blackwell. pp. 112, 203–204. ISBN 978-1-118-67746-9.
- ^ a b c Haines, Duane E. (January 2013). Fundamental Neuroscience for Basic and Clinical Applications, with STUDENT CONSULT Online Access,4: Fundamental Neuroscience for Basic and Clinical Applications. Elsevier Health Sciences. p. 423. ISBN 978-1-4377-0294-1.
- ^ a b James D. Fix. High-Yield Neuroanatomy 4th Edition. Wolters Kluwer, Lippincott Williams and Wilkins. pp. 63-64.
- ^ Le, Tao (2023). First Aid. McGraw Hill.
