| trigeminal nucleus, spinal | Nucleus of the spinal tract of the trigeminal nerve. It is divided cytoarchitectonically into three parts: oralis, caudalis (trigeminal caudal nucleus), and interpolaris. (12 Dec 1998) |
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| trochlear nucleus | 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) |
| trophic nucleus | The larger nucleus (or sometimes nuclei) in ciliate protozoans. Derived from the micronucleus by a process of DNA polytenisation. The DNA in the macronucleus is actively transcribed. The macronucleus degenerates before conjugation. (18 Nov 1997) |
| tubercle of nucleus gracilis | tubercle of gracile nucleus |
| external 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) |
| facial motor nucleus | 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) |
| facial nucleus | 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) |
| fastigial nucleus | The most medial of the cerebellar nuclei, lying medial to the interpositus nucleus, near the midline, in the white matter underneath the vermis of the cerebellar cortex. It receives the axons of Purkinje cells from all parts of the vermis. Its major projection is to the vestibular nuclei and medullary reticular formation. Synonym: nucleus fastigii, fastigatum, nucleus tecti, roof nucleus, tectal nucleus. (05 Mar 2000) |
| filiform nucleus | 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) |
| lateral 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) |
| lateral nucleus of medulla oblongata | 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) |
| lateral preoptic nucleus | A vaguely defined group of nerve cells in the lateral zone of the preoptic region. Synonym: nucleus preopticus lateralis. (05 Mar 2000) |
| lateral reticular nucleus | 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) |
| lateral vestibular nucleus | Nucleus vestibularis lateralis. See: vestibular nucleus. (05 Mar 2000) |
| lens nucleus, crystalline | The core of the crystalline lens, surrounded by the cortex. (12 Dec 1998) |