| 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) |
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| 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 |
| arcuate nucleus | A nucleus located in the middle hypothalamus in the most ventral part of the third ventricle near the entrance of the infundibular recess. Its small cells are in close contact with the ependyma. (12 Dec 1998) |
| arcuate nucleus of thalamus | The small ventral region of the ventral posteromedial nucleus of thalamus in which the fibres of the gustatory lemniscus and secondary trigeminal tracts terminate; it projects to the lower part of the postcentral gyrus of the cerebral cortex. Synonym: arcuate nucleus, nucleus arcuatus thalami, nucleus arcuatus, semilunar nucleus of Flechsig, thalamic gustatory nucleus. (05 Mar 2000) |
| basal nucleus of Ganser | A large group of large cells in the innominate substance, ventral to the lentiform nucleus. Synonym: nucleus basalis of Ganser. (05 Mar 2000) |
| Bechterew's nucleus | See: vestibular nucleus. Synonym: nucleus centralis tegmenti superior. (05 Mar 2000) |
| benzene nucleus | The six conjugated carbon atoms of the benzene ring. (05 Mar 2000) |
| Blumenau's nucleus | The lateral cuneate nucleus of the medulla oblongata. (05 Mar 2000) |