| spherical nucleus | Spinal nucleus of accessory nerve, a slender column of motor neurons extending longitudinally through the central part of the ventral horn of the upper five segments of the spinal cord, giving origin to the spinal part of the accessory nerve. Synonym: nucleus spinalis nervi accessorii, globosus nucleus. (05 Mar 2000) |
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| spinal nucleus of the trigeminus | 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) |
| spinal trigeminal nucleus | 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) |
| Spitzka's nucleus | A small cell group located between the somatic cell columns of the oculomotor nuclei. Since it is placed between the groups of motor neurons innervating, respectively, the left and right medial rectus muscles, the nucleus is considered to possibly represent an integrating mechanism for ocular convergence. Synonym: convergence nucleus of Perlia, Spitzka's nucleus. (05 Mar 2000) |
| Staderini's nucleus | A small collection of nerve cells in the medulla oblongata lying lateral to the hypoglossal nucleus. Synonym: nucleus intercalatus, Staderini's nucleus. (05 Mar 2000) |
| steroid nucleus | tetracyclic steroid nucleus |
| Stilling's nucleus | 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) |
| subceruleus nucleus | Diffusely organised nucleus of noradrenergic cells located ventral to the nucleus (locus) ceruleus. (05 Mar 2000) |
| subthalamic nucleus | 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) |
| nucleus | The major organelle of eukaryotic cells, in which the chromosomes are separated from the cytoplasm by the nuclear envelope. (18 Nov 1997) |
| nucleus accumbens | The largest neuronal nucleus in the septal region of the diencephalon. (12 Dec 1998) |
| nucleus accumbens septi | The region of fusion between the head of the caudate nucleus and the putamen, covered on the ventral side by the olfactory tubercle. The name ("a nucleus leaning against the septum") refers to a medial, hook-shaped expansion of this anteroventral region of the striatum which curves under the floor of the frontal horn of the lateral ventricle and ascends for some distance into the ventral half of the septal region. (05 Mar 2000) |
| nucleus acusticus | An obsolete term for the combined vestibular and cochlear nuclei. (05 Mar 2000) |
| nucleus alae cinereae | The visceral motor nucleus located in the vagal trigone (ala cinerea) of the floor of the fourth ventricle. It gives rise to the parasympathetic fibres of the vagus nerve innervating the heart muscle and the smooth musculature and glands of the respiratory and intestinal tracts. Synonym: nucleus dorsalis nervi vagi, dorsal motor nucleus of vagus, dorsal nucleus of vagus, dorsal vagal nucleus, nucleus alae cinereae. (05 Mar 2000) |
| nucleus ambiguus | A very slender, longitudinal column of motor neurons in the ventrolateral medulla oblongata; its efferent fibres leave with the vagus and glossopharyngeal nerve and innervate the striated muscle fibres of the pharynx (including the musculus levator veli palatini) and the vocal cord muscles of the larynx. Synonym: ambiguous nucleus. (05 Mar 2000) |