| nucleus of lateral lemniscus | A substantial cell mass embedded in the lateral lemniscus, immediately below the latter's entry into the inferior colliculus; the nucleus represents a synaptic way-station for part of the fibres of the lateral lemniscus. Synonym: nucleus lemnisci lateralis. (05 Mar 2000) |
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| nucleus of lens | The core or inner dense portion of the lens of the eye. Synonym: nucleus of lens. (05 Mar 2000) |
| nucleus of Luys | 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 of medial geniculate body | The nerve cell groups composing the medial geniculate body (corpus geniculatum mediale). Synonym: nucleus corporis geniculati medialis. (05 Mar 2000) |
| nucleus of oculomotor nerve | The composite group of motor neurons innervating all of the external eye muscles except the musculus rectus lateralis and musculus obliquus superior, and including the musculus levator palpebrae superioris; the most rostral component of the nucleus is the Edinger-Westphal nucleus which innervates the musculi sphincter pupillae and ciliaris via the ciliary ganglion. The oculomotor nucleus lies in the rostral half of the midbrain, near the midline in the most ventral part of the central gray substance; fibres of the medial longitudinal fasciculus form its lateral borders. Synonym: nucleus nervi oculomotorii, nucleus of oculomotor nerve. (05 Mar 2000) |
| nucleus of solitary tract | 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 of the mamillary body | A single large-celled lateral nucleus and a larger bipartite medial nucleus together comprising the mamillary body; present in the caudal hypothalamus. Synonym: nuclei corporis mamillaris, nucleus of the mamillary body. (05 Mar 2000) |
| nucleus of trochlear nerve | A group of motor neurons innervating the superior oblique muscle of the contralateral eye. The nucleus lies in the caudal half of the midbrain, behind the oculomotor nucleus, in the most ventral part of the central gray substance, near the midline. Synonym: nucleus nervi trochlearis, nucleus of trochlear nerve. (05 Mar 2000) |
| nucleus paracentralis thalami | One of the intralaminar nuclei of the thalamus, medial to the central lateral nucleus. Synonym: nucleus paracentralis thalami. (05 Mar 2000) |
| nucleus paraventricularis | A triangular group of large magnocellular neurons in the periventricular zone of the anterior half of the hypothalamus. The cells of the nucleus are similar to those of the supraoptic nucleus; the axons of about 20% of their number join in the formation of the supraopticohypophysial tract and are functionally associated with the posterior lobe of the hypophysis; they project fibres to the brainstem nuclei (dorsal motor nucleus and solitary nucleus) and to the intermediolateral cell column of the spinal cord at thoracic, lumbar, and spinal levels; similar descending autonomic fibres arise from the lateral and posterior hypothalamic nuclei. Synonym: nucleus paraventricularis, filiform nucleus, nucleus filiformis. (05 Mar 2000) |
| nucleus posterior hypothalami | A large, periventricular hypothalamic nucleus located dorsal to the mamillary body, continuous with the central gray substance of the mesencephalon. Synonym: nucleus posterior hypothalami. (05 Mar 2000) |
| nucleus preopticus lateralis | A vaguely defined group of nerve cells in the lateral zone of the preoptic region. Synonym: nucleus preopticus lateralis. (05 Mar 2000) |
| nucleus preopticus medialis | A group of nerve cells forming the medial zone of the preoptic region. Synonym: nucleus preopticus medialis. (05 Mar 2000) |
| nucleus pulposus | The soft fibrocartilage central portion of the intervertebral disk; regarded as a derivative of the notochord. Synonym: gelatinous nucleus, nucleus gelatinosus, vertebral pulp. (05 Mar 2000) |
| nucleus pyramidalis | An obsolete term for nucleus olivaris accessorius medialis. (05 Mar 2000) |