| 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) |
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| 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) |
| principal sensory nucleus of the trigeminus | <anatomy, nerve> The term commonly used to designate the nucleus pontis nervi trigeminalis; located in pons lateral to the motor trigeminal nucleus; receives primary sensory (touch and pressure) input via the trigeminal nerve, projects to ventral posteromedial nucleus of thalamus. Synonym: nucleus sensorius principalis nervi trigemini, nucleus sensorius superior nervi trigemini, principal sensory nucleus of the trigeminus. (05 Mar 2000) |
| principal sensory nucleus of trigeminal nerve | <anatomy, nerve> The term commonly used to designate the nucleus pontis nervi trigeminalis; located in pons lateral to the motor trigeminal nucleus; receives primary sensory (touch and pressure) input via the trigeminal nerve, projects to ventral posteromedial nucleus of thalamus. Synonym: nucleus sensorius principalis nervi trigemini, nucleus sensorius superior nervi trigemini, principal sensory nucleus of the trigeminus. (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) |
| semilunar nucleus of Flechsig | 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) |
| pyrrole nucleus | Of porphyrins, a cyclic tetrapyrrole; four pyrrole groups joined into a ring structure by way of -CH== (methylidyne) bridges between the a position of one pyrrole and the a' position of another pyrrole, the fourth pyrrole being joined to the first. See: porphin, porphyrin. (05 Mar 2000) |
| shadow nucleus | A nucleus that has lost its pigment and staining properties. (05 Mar 2000) |
| hypoglossal nucleus | 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) |