| nucleus subthalamicus | A circumscript nucleus, shaped like a biconvex lens, located in the ventral part of the subthalamus on the dorsal surface of the peduncular part of the internal capsule immediately rostral to the substantia nigra. The nucleus receives a massive topographic projection from the lateral segment of the globus pallidus, and a somatopically organised projection from the ipsilateral motor cortex; a smaller bundle of afferents from the centromedian nucleus of the thalamus terminate in the rostral part of the nucleus The subthalamic nucleus projects to both pallidal segments, to the pars reticulata of the substantia nigra, and in a small way to the ipsilateral pedunculopontine nucleus. Synonym: nucleus subthalamicus, corpus luysi, Luys' body, nucleus of Luys. (05 Mar 2000) |
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| nucleus suprachiasmatica | Small nucleus located dorsal to the optic chiasm; receives input from retina, influences hypothalamic neuroendocrine function; closely associated with regulation of circadian rhythmicity. (05 Mar 2000) |
| nucleus supraopticus hypothalami | A large-celled neurosecretory nucleus in the hypothalamus, located over the lateral border of the optic tract, from which the supraopticohypophysial tract arises; its neurons produce and transport vasopressin released into the general circulation from the axon terminals in the supraopticohypophysial tract. Synonym: nucleus supraopticus hypothalami, supraoptic nucleus. (05 Mar 2000) |
| nucleus tecti | The most medial of the cerebellar nuclei, lying medial to the interpositus nucleus, near the midline, in the white matter underneath the vermis of the cerebellar cortex. It receives the axons of Purkinje cells from all parts of the vermis. Its major projection is to the vestibular nuclei and medullary reticular formation. Synonym: nucleus fastigii, fastigatum, nucleus tecti, roof nucleus, tectal nucleus. (05 Mar 2000) |
| nucleus thoracicus | A column of large neurons located in the base of the posterior gray column of the spinal cord, extending from the first thoracic through the second lumbar segment; it gives rise to the dorsal spinocerebellar tract of the same side. Synonym: nucleus thoracicus, Clarke's column, Clarke's nucleus, dorsal nucleus, nucleus dorsalis, Stilling's column, Stilling's nucleus. (05 Mar 2000) |
| nucleus tractus mesencephali nervi trigemini | <anatomy, nerve> A long, narrow plate of unipolar neurons extending throughout the length of the midbrain, in and along the lateral angle of the central gray substance. The nucleus is the single known instance of primary sensory neurons enclosed in the central nervous system instead of in a peripheral sensory ganglion. Its peripheral axonal processes pass with the trigeminal nerve, give collaterals to the trigeminal motor nucleus, and terminate in the muscles of mastication. Synonym: nucleus tractus mesencephali nervi trigemini. (05 Mar 2000) |
| nucleus tractus solitarii | A slender cell column extending sagittally through the dorsal part of the medulla oblongata, beneath the floor of the rhomboid fossa, immediately lateral to the limiting sulcus. It is the visceral sensory (visceral afferent) nucleus of the brainstem, receiving the afferent fibres of the vagus, glossopharyngeal, and facial nerves by way of the solitary tract. The caudal two-thirds of the nucleus processes impulses originating in the pharynx, larynx, intestinal and respiratory tracts, and heart and large blood vessels; its rostral one-third receives impulses from the taste buds and is known as the rhombencephalic gustatory nucleus. Synonym: nucleus tractus solitarii. (05 Mar 2000) |
| nucleus tractus spinalis nervi trigemini | The long sensory nucleus extending from the caudal border of the pontine sensory nucleus of the trigeminus down through the lateral region of the rhombencephalon into the upper three segments of the spinal cord's dorsal horn; it receives the fibres of the sensory root of the trigeminal nerve which descend along its lateral border as the spinal tract of trigeminal nerve. Synonym: nucleus tractus spinalis nervi trigemini, descending nucleus of the trigeminus, spinal nucleus of the trigeminus. (05 Mar 2000) |
| nucleus ventromedialis hypothalami | <anatomy> A circumscript ovoid group of small neurons in the medial zone of the tuberal region of the hypothalamus. Bilateral destruction of this nucleus in the rat leads to severe obesity. It receives numerous fibres from the amygdala via the terminal stria; its efferent connections are obscure. Synonym: nucleus ventromedialis hypothalami. (05 Mar 2000) |
| nucleus vestibularis | One of a group of four main nuclei that includes: the lateral vestibular nucleus (Deiters' nucleus), medial vestibular nucleus (Schwalbe's nucleus), superior vestibular nucleus (Bechterew's nucleus), and inferior vestibular nucleus, located in the lateral region of the hindbrain beneath the floor of the rhomboid fossa. They receive primary fibres of the vestibular nerve, are reciprocally connected with the flocculonodular lobe of the cerebellum, and project by way of the medial longitudinal fasciculus to the abducens, trochlear, and oculomotor nuclei and to the ventral horn of the spinal cord. The lateral vestibular nucleus projects to the ipsilateral ventral horn of the spinal cord by the vestibulospinal tract. Synonym: nucleus vestibularis. (05 Mar 2000) |
| superior central tegmental nucleus | Collections of small neurons centrally scattered among many fibres from the level of the trochlear nucleus in the midbrain to the hypoglossal area in the medulla oblongata. (12 Dec 1998) |
| superior olivary nucleus | A circumscript, bipartite cell group located ventrolaterally in the lower pontine tegmentum, immediately dorsal to the trapezoid body; the nucleus receives fibres from both the ipsilateral and contralateral cochlear nuclei, and contributes fibres to the lateral (auditory) lemniscus of both sides. It is believed to be prominently involved in the function of spatial localization of sound. Synonym: nucleus dorsalis corporis trapezoidei, oliva superior, superior olivary nucleus, superior olive. (05 Mar 2000) |
| superior salivary nucleus | A group of preganglionic parasympathetic motor neurons situated rostral and lateral to the inferior salivatory nucleus; it governs secretion of the lacrimal, sublingual, and submaxillary glands by way of the facial nerve and the sphenopalatine and submandibular ganglia. Synonym: nucleus salivatorius superior, superior salivary nucleus. (05 Mar 2000) |
| superior salivatory nucleus | A group of preganglionic parasympathetic motor neurons situated rostral and lateral to the inferior salivatory nucleus; it governs secretion of the lacrimal, sublingual, and submaxillary glands by way of the facial nerve and the sphenopalatine and submandibular ganglia. Synonym: nucleus salivatorius superior, superior salivary nucleus. (05 Mar 2000) |
| superior vestibular nucleus | One of a group of four main nuclei that includes: the lateral vestibular nucleus (Deiters' nucleus), medial vestibular nucleus (Schwalbe's nucleus), superior vestibular nucleus (Bechterew's nucleus), and inferior vestibular nucleus, located in the lateral region of the hindbrain beneath the floor of the rhomboid fossa. They receive primary fibres of the vestibular nerve, are reciprocally connected with the flocculonodular lobe of the cerebellum, and project by way of the medial longitudinal fasciculus to the abducens, trochlear, and oculomotor nuclei and to the ventral horn of the spinal cord. The lateral vestibular nucleus projects to the ipsilateral ventral horn of the spinal cord by the vestibulospinal tract. Synonym: nucleus vestibularis. (05 Mar 2000) |