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]
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]
The tract descends through the periaqueductal gray, [5] through the dorsal longitudinal fasciculus, [1] and adjacent to the reticular formation. [5] It 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]
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]
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]
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]
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]
The tract descends through the periaqueductal gray, [5] through the dorsal longitudinal fasciculus, [1] and adjacent to the reticular formation. [5] It 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]
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]
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]