| 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) |
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| 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 motorius nervi trigemini | <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 nervi abducentis | Nucleus of abducent nervenucleus abducentis, a group of motor neurons in the lower part of the pons, innervating the lateral rectus muscle of the eye; unique among motor cranial nerve nuclei in that it consists of two distinct populations of neurons: neurons that give rise to fibres forming the abducens nerve root and those internuclear neurons whose processes cross the midline, ascend in the opposite medial longitudinal fasciculus, and terminate upon specific oculomotor neurons; considered a primary centre for mechanisms controlling conjugate horizontal gaze. Synonym: nucleus nervi abducentis. (05 Mar 2000) |
| nucleus nervi facialis | A group of motor neurons located in the ventrolateral region of the lower pontine tegmentum and innervating the facial muscles, the stapedius muscle in the middle ear, the posterior limb of the musculus digastricus, and the stylohyoid muscle. Synonym: nucleus nervi facialis, facial motor nucleus, motor nucleus of facial nerve, nucleus facialis. (05 Mar 2000) |
| nucleus nervi hypoglossi | The motor nucleus innervating the intrinsic and four of the five extrinsic muscles of the tongue; it is located in the medulla oblongata near the midline, immediately beneath the floor of the inferior recess of the rhomboid fossa. Synonym: nucleus nervi hypoglossi, nucleus of hypoglossal nerve. (05 Mar 2000) |
| nucleus nervi oculomotorii | 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 nervi trochlearis | 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) |