| reticular membrane | The membrane formed by cuticular plates of the cells of the spiral organ of Corti; it appears netlike when viewed from above. Synonym: membrana reticularis. (05 Mar 2000) |
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| reticular nuclei of the brainstem | The vaguely delineated cell groups composing the gray matter of the reticular formation of the rhombencephalon and mesencephalon. In general, large-celled territories occupy the medial two-thirds of the reticular formation: gigantocellular nucleus of medulla oblongata, nuclei tegmenti pontis caudalis and oralis. Smaller groups of reticular nuclei are found laterally and in paramedian locations; lateral nuclei receive sensory collaterals and project medially; paramedian reticular nuclei largely project to the cerebellum. See: reticular formation. (05 Mar 2000) |
| reticular substance | A filamentous plasmatic material, beaded with granules, demonstrable by means of vital staining in the immature red blood cells. Synonym: alpha substance, filar mass, filar substance, substantia reticularis, substantia reticulofilamentosa. Synonym: reticular formation. (05 Mar 2000) |
| reticular tissue | Retiform tissue, a tissue in which the argyrophilic collagenous fibres form a network and that usually has a network of reticular cells associated with the fibres. (05 Mar 2000) |
| primitive reticular cell | A cell with processes making contact with those of other similar cell's to form a cellular network; along with the network of reticular fibres, the reticular cell's form the stroma of bone marrow and lymphatic tissues. (05 Mar 2000) |
| epithelial reticular cell | One of the many-branched epithelial cell's that collectively form the supporting stroma for lymphocytes in the thymus; believed to produce thymosin and other factors that control thymic function. (05 Mar 2000) |
| abducens nucleus | 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) |
| accessory cuneate nucleus | A cell group lateral to the cuneate nucleus which receives posterior-root fibres corresponding to the proprioceptive innervation of the arm and hand; it projects to the cerebellum by way of the cuneocerebellar tract, and can be considered the upper-extremity equivalent of the thoracic nucleus. Synonym: nucleus cuneatus accessorius, external cuneate nucleus, lateral cuneate nucleus, Monakow's nucleus. (05 Mar 2000) |
| almond nucleus | Almond-shaped group of basal nuclei anterior to the inferior horn of the lateral ventricle of the brain, within the temporal lobe. The amygdala is part of the limbic system. (12 Dec 1998) |
| ambiguous nucleus | 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) |
| amygdaloid nucleus | Almond-shaped group of basal nuclei anterior to the inferior horn of the lateral ventricle of the brain, within the temporal lobe. The amygdala is part of the limbic system. (12 Dec 1998) |
| anterior extremity of caudate nucleus | The head or anterior extremity of the caudate nucleus projecting into the anterior horn of the lateral ventricle. Synonym: caput nuclei caudati, anterior extremity of caudate nucleus. (05 Mar 2000) |
| anterodorsal thalamic nucleus | anterodorsal thalamic nucleus |
| anteromedial thalamic nucleus | anteromedial thalamic nucleus |
| anteroventral thalamic nucleus | anteroventral thalamic nucleus |