| habenular nucleus | 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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| posterior hypothalamic nucleus | A large, periventricular hypothalamic nucleus located dorsal to the mamillary body, continuous with the central gray substance of the mesencephalon. Synonym: nucleus posterior hypothalami. (05 Mar 2000) |
| posterior medial nucleus of thalamus | Medial part of the ventrobasal nuclear complex. See: ventral posterior nucleus of thalamus. Synonym: nucleus ventralis posteromedialis thalami. (05 Mar 2000) |
| posterior periventricular 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) |
| cuneate nucleus | The larger Burdach's nucleus; one of the three nuclei of the posterior column of the spinal cord; located near the dorsal surface of the medulla oblongata at and below the level of the obex, the nucleus receives posterior root fibres corresponding to the sensory innervation of the arm and hand of the same side; together with its medial companion, the gracile nucleus, it is the major source of origin of the medial lemniscus. Synonym: nucleus cuneatus, Burdach's nucleus, nucleus funiculi cuneati, nucleus of cuneate fasciculus. (05 Mar 2000) |
| prerubral nucleus | The gray matter of field H2. See: fields of Forel. (05 Mar 2000) |
| pretectal nucleus | Group of cells, constituting several subnuclei, located rostral to the superior colliculus in the "pretectal" area; receive input from retinal ganglion cells (via the optic tract) and project bilaterally to the Edinger-Westphal nucleus; relay centre for pupillary light reflex pathway. (05 Mar 2000) |
| head of the 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) |
| herniated nucleus pulposus | <orthopaedics> A herniated intervertebral disk (nucleus pulposus) is one which has become displaced (prolapsed) from its normal position in between the vertebral bodies of the spine. Herniated disks often impinge on nearby nerve structures resulting in pain and neurologic symptoms. A clinical situation where the radicular nerve (nerve root) is compressed by the prolapsed disk is referred to as a radiculopathy. This problem tends to occur most commonly in the cervical and lumbar spine. (27 Sep 1997) |
| herniation of nucleus pulposus | <radiology> Focal protrusion of disc material secondary to rupture of annulus fibrosus confined within the posterior longitudinal ligament location: L4/5 (35%); L5/S1 (27%); L3/4 (19%); L2/3 (14%); L1/2 (5%); thoracic spine affected in 3:1000 disc operations, posterolateral (49%): weakest point (posterior longitudinal ligament tightly adherent to posterior margin of disc), posterocentral (8%), lateral/foraminal (less than10%), intraosseous/vertical (14%): Schmorl node, extraforaminal/anterior (29%): commonly overlooked, bilateral: on both sided of the posterior ligament findings: disc (low T1) displaces posterior ligament/epidural fat (high T1), enlarged (edematous) nerve root: trumpet sign, see: degenerative disc disease extradural mass (12 Dec 1998) |
| Schwalbe's nucleus | One of a group of four main nuclei that includes: the lateral vestibular nucleus (Deiters' nucleus), medial vestibular nucleus (Schwalbe's nucleus), superior vestibular nucleus (Bechterew's nucleus), and inferior vestibular nucleus, located in the lateral region of the hindbrain beneath the floor of the rhomboid fossa. They receive primary fibres of the vestibular nerve, are reciprocally connected with the flocculonodular lobe of the cerebellum, and project by way of the medial longitudinal fasciculus to the abducens, trochlear, and oculomotor nuclei and to the ventral horn of the spinal cord. The lateral vestibular nucleus projects to the ipsilateral ventral horn of the spinal cord by the vestibulospinal tract. Synonym: nucleus vestibularis. (05 Mar 2000) |
| hilum of dentate nucleus | The mouth of the flasklike dentate nucleus of the cerebellum, directed inward, and giving exit to many of the fibres which compose the superior cerebellar peduncle or brachium conjunctivum. Synonym: hilum nuclei dentati. (05 Mar 2000) |
| hilum of olivary nucleus | The medially oriented opening in the folded cell layer composing the inferior olivary nucleus through which the efferent fibres of the nucleus make their exit. Synonym: hilum nuclei olivaris. (05 Mar 2000) |
| segmentation nucleus | The compound nucleus in the impregnated ovum, formed by conjugation of the nuclei of the ovum and spermatozoon (female and male pronuclei), the zygote nucleus after it commences the first cleavage division. (05 Mar 2000) |
| pulvinar nucleus | The large caudal portion of the lateral thalamic nuclear group; may be divided into oral, inferior, medial and lateral parts based on cytoarchitecture and connections; functionally related to the visual system. (05 Mar 2000) |