Hypothalamospinal tract

[1][3] 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.[6] 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.[1] 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.
Anatomical terminologyunmyelinatednerve tractbrainstemspinal cordpre-ganglionicautonomicsympatheticparasympatheticparaventricular nucleus of hypothalamusdorsomedialventromedialposterior nuclei of hypothalamuslateral hypothalamusspinohypothalamic tractperiaqueductal graydorsal longitudinal fasciculusreticular formationtegmentummidbrainmedulla oblongatalateral funiculussuperior cervical ganglionhypothalamusciliospinal centerpupillary dilatationpupillary reflexoxytocinHorner's syndromeElsevier