| nucleus habenulae | The gray matter of the habenula, composed of a small-celled medial and a larger-celled lateral habenular nucleus; both nuclei receive fibres from basal forebrain regions (septum, basal nucleus, lateral preoptic nucleus); the lateral habenular nucleus receives an additional projection from the medial segment of the globus pallidus. Both nuclei project by way of the retroflex fasciculus to the interpeduncular nucleus and a medial zone of the midbrain tegmentum. Synonym: nucleus habenulae, ganglion habenulae. (05 Mar 2000) |
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| nucleus intercalatus | 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) |
| nucleus intermediolateralis | The cell column that forms the lateral horn of the spinal cord's gray matter. Extending from the first thoracic through the second lumbar segment, the column contains the autonomic motor neurons that give rise to the preganglionic fibres of the sympathetic system. Synonym: intermediolateral cell column of spinal cord, nucleus intermediolateralis. (05 Mar 2000) |
| nucleus intermediomedialis | A small group of scattered visceral motor neurons immediately ventral to the thoracic nucleus in the thoracic and upper two lumbar segments of the spinal cord; considered to receive visceral afferent fibres at all spinal levels. Synonym: nucleus intermediomedialis. (05 Mar 2000) |
| nucleus interpeduncularis | A median, unpaired, ovoid cell group at the base of the midbrain tegmentum between the cerebral peduncles; it receives the retroflex fasciculus from the habenula, and projects to the raphe region (raphe nuclei) and periaqueductal gray substance of the midbrain. Synonym: nucleus interpeduncularis, ganglion isthmi, Gudden's ganglion, intercrural ganglion, interpeduncular ganglion. (05 Mar 2000) |
| nucleus interpositus | Collective term denoting the combined globosus nuclei and emboliform nuclei of the cerebellum; more correctly used as interposed nuclei as it identifies two cell groups. Synonym: nucleus interpositus. (05 Mar 2000) |
| nucleus interstitialis | A group of widely spaced, medium-sized neurons in the dorsomedial region of the upper mesencephalic tegmentum, immediately lateral to the nucleus of Darkschewitsch; together with the latter, the interstitial nucleus is closely associated with the medial longitudinal fasciculus, via which it receives fibres from the vestibular nuclei and projects crossed fibres via the posterior commissure to the oculomotor nucleus; also projects fibres to all spinal levels. It is believed to be involved in the integration of head and eye movements, particularly eye movements of a vertical or oblique nature. Synonym: nucleus interstitialis, interstitial nucleus of Cajal. (05 Mar 2000) |
| nucleus lateralis medullae oblongatae | A group of cells in the medulla oblongata, located between the inferior olive and the descending trigeminal nucleus, receiving fibres from the spinal cord and motor cortex and projecting to the cerebellum. Synonym: nucleus lateralis medullae oblongatae, lateral reticular nucleus. (05 Mar 2000) |
| nucleus lateralis thalami | The largest of the major subdivisions of the thalamus; the composite lateral nucleus includes, from before backward, the nucleus lateralis anterior or dorsalis, nucleus lateralis intermedius, nucleus lateralis posterior, and pulvinar; together, these cell groups form most of the free dorsal surface of the posterior half of the thalamus and project to a very large region of parietal, occipitoparietal, and temporal cortex; its afferent connections are largely obscure, but the nucleus lateralis posterior and the pulvinar receive a projection from the superior colliculus. Synonym: nucleus lateralis thalami. (05 Mar 2000) |
| nucleus lemnisci lateralis | 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) |
| nucleus lentiformis | Lentiform nucleus, the large cone-shaped mass of gray matter forming the central core of the cerebral hemisphere. The convex base of the cone, oriented laterally and rostrally, is formed by the putamen which together with the caudate nucleus composes the striatum; the apical part, oriented medially and caudally, consists of the two segments of the globus pallidus. The nucleus is ventral and lateral to the thalamus and caudate nucleus, from which it is separated by the internal capsule, and together with the caudate nucleus composes the striate body. Synonym: nucleus lentiformis, lenticula. (05 Mar 2000) |
| nucleus lentis | The core or inner dense portion of the lens of the eye. Synonym: nucleus of lens. (05 Mar 2000) |
| nucleus masticatorius | <anatomy, nerve> A group of motor neurons innervating the muscles of mastication (masseter, temporalis, internal and external pterygoid muscles) and the musculi tensor tympani and tensor veli palatini. The nucleus lies in the upper pontine tegmentum medial to the main sensory nucleus of the trigeminus. Synonym: nucleus motorius nervi trigemini, masticatory nucleus, motor nucleus of trigeminus, nucleus masticatorius. (05 Mar 2000) |
| nucleus medialis centralis thalami | A small cell group in the interthalamic adhesion of the thalamus, occupying the midline region of the internal medullary lamina, between the left and the right paracentral nucleus. Synonym: nucleus medialis centralis thalami. (05 Mar 2000) |
| nucleus medialis thalami | A large, composite cell group in the dorsomedial region of the thalamus having reciprocal connections with the entire extent of the frontal cortex anterior to the motor cortex (area 4) and premotor cortex (area 6). The afferent connections of the medial nucleus also include projections from the olfactory cortex and amygdala. Synonym: nucleus medialis thalami, dorsomedial nucleus, mediodorsal nucleus. (05 Mar 2000) |