| fasciculus marginalis | A longitudinal bundle of thin, unmyelinated and poorly myelinated fibres capping the apex of the posterior horn of the spinal gray matter, composed of posterior root fibres and short association fibres that interconnect neighboring segments of the posterior horn. Synonym: fasciculus dorsolateralis, tractus dorsolateralis, dorsolateral tract, fasciculus marginalis, Lissauer's bundle, Lissauer's column, Lissauer's fasciculus, Lissauer's marginal zone, Lissauer's tract, marginal fasciculus, Spitzka's marginal tract, Spitzka's marginal zone, Waldeyer's tract, Waldeyer's zonal layer. (05 Mar 2000) |
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| fasciculus medialis plexus brachialis | In the brachial plexus, the bundle of nerve fibres formed by the anterior division of the inferior trunk which lies medial to the axillary artery; it gives off the medial pectoral nerve, the medial brachial cutaneous, and medial antebrachial cutaneous, nerves and end by dividing into the medial root of the median nerves and the ulnar nerve. Synonym: fasciculus medialis plexus brachialis. (05 Mar 2000) |
| fasciculus obliquus pontis | A bundle of fibres in the ventral surface of the pons running from the anterior mesial portion outward and backward. Synonym: fasciculus obliquus pontis, oblique bundle of pons. (05 Mar 2000) |
| fasciculus occipitofrontalis | A bundle of association fibres extending from the frontal to the occipital lobes of the cerebrum. Synonym: fasciculus occipitofrontalis, fronto-occipital fasciculus. (05 Mar 2000) |
| fasciculus pedunculomamillaris | A fascicle of nerve fibres passing to the mamillary body along the ventral surface of the midbrain; it consists of fibres that originate from the dorsal and ventral tegmental nuclei. Synonym: pedunculus corporis mamillaris, fasciculus pedunculomamillaris, pedunculomamillary fasciculus. (05 Mar 2000) |
| fasciculus posterior plexus brachialis | In the brachial plexus, the bundle of nerve fibres formed by the posterior divisions of the upper, middle and lower trunks which lies posterior to the axillary artery; it gives rise to the upper and lower subscapular and thoracodorsal nerves, terminates by dividing into the axillary, and radial nerves. Synonym: fasciculus posterior plexus brachialis. (05 Mar 2000) |
| fasciculus pyramidalis lateralis | Those fibres of the pyramidal tract that cross to the opposite side in the pyramidal decussation and descend in the dorsal half of the lateral funiculus of the spinal cord; they are distributed throughout the length of the spinal cord to interneurons of the zona intermedia of the spinal gray matter. See: pyramidal tract. Synonym: tractus corticospinalis lateralis, tractus pyramidalis lateralis, crossed pyramidal tract, fasciculus corticospinalis lateralis, fasciculus pyramidalis lateralis, lateral corticospinal tract, lateral pyramidal fasciculus. (05 Mar 2000) |
| fasciculus retroflexus | A compact bundle of fibres arising in the habenula and passing ventralward to the interpeduncular nucleus at the base of the midbrain; part of its fibres bypass this nucleus and terminate in the raphe nuclei of the caudal mesencephalic tegmentum. Synonym: fasciculus retroflexus, habenulointerpeduncular tract, Meynert's fasciculus, Meynert's retroflex bundle. (05 Mar 2000) |
| fasciculus rotundus | A slender, compact fibre bundle extending longitudinally through the dorsolateral region of the medullary tegmentum, surrounded by the nucleus of the solitary tract, below the obex decussating over the central canal, and descending over some distance into the upper cervical segments of the spinal cord. It is composed of primary sensory fibres that enter with the vagus, glossopharyngeal, and facial nerves, and in part convey information from stretch receptors and chemoreceptors in the walls of the cardiovascular, respiratory, and intestinal tracts; in rostral parts of the tract impulses are generated by the receptor cells of the taste buds in the mucosa of the tongue. Its fibres are distributed to the nucleus of the solitary tract. Synonym: tractus solitarius, fasciculus rotundus, fasciculus solitarius, funiculus solitarius, Gierke's respiratory bundle, Krause's respiratory bundle, round fasciculus, solitary bundle, solitary fasciculus. (05 Mar 2000) |
| fasciculus semilunaris | A compact bundle composed of descending branches of posterior root fibres located near the border between the fasciculi gracilis and cuneatus of the cervical and thoracic spinal cord; it corresponds to the septomarginal fasciculus, Hoche's tract, or oval area of Flechsig in the lumbar, and to the triangle of Philippe-Gombault in the sacral spinal segments; like these, it can be demonstrated only in cases of demyelination resulting from dorsal root lesions. Synonym: fasciculus semilunaris, fasciculus interfascicularis, comma bundle of Schultze, comma tract of Schultze, interfascicular fasciculus. (05 Mar 2000) |
| fasciculus septomarginalis | Septomarginal fasciculus or tract. Synonym: fasciculus septomarginalis. (05 Mar 2000) |
| fasciculus solitarius | A slender, compact fibre bundle extending longitudinally through the dorsolateral region of the medullary tegmentum, surrounded by the nucleus of the solitary tract, below the obex decussating over the central canal, and descending over some distance into the upper cervical segments of the spinal cord. It is composed of primary sensory fibres that enter with the vagus, glossopharyngeal, and facial nerves, and in part convey information from stretch receptors and chemoreceptors in the walls of the cardiovascular, respiratory, and intestinal tracts; in rostral parts of the tract impulses are generated by the receptor cells of the taste buds in the mucosa of the tongue. Its fibres are distributed to the nucleus of the solitary tract. Synonym: tractus solitarius, fasciculus rotundus, fasciculus solitarius, funiculus solitarius, Gierke's respiratory bundle, Krause's respiratory bundle, round fasciculus, solitary bundle, solitary fasciculus. (05 Mar 2000) |
| fasciculus subcallosus | A bundle of thin nerve fibres running longitudinally beneath the corpus callosum in the angle between the latter and the caudate nucleus; it forms an anterior continuation of the tapetum of the temporal lobe and appears to consist largely of fibres projecting from the cerebral cortex to the caudate nucleus. Synonym: fasciculus subcallosus. (05 Mar 2000) |
| fasciculus thalamicus | Nerve fibres forming a composite bundle containing cerebellothalamic (crossed) and pallidothalamic (uncrossed) fibres that is insinuated between the thalamus and zona incerta. See: fields of Forel. Synonym: fasciculus thalamicus. (05 Mar 2000) |
| fasciculus thalamomamillaris | A compact, thick bundle of nerve fibres that passes dorsalward from the mamillary body on either side to terminate in the anterior nucleus of the thalamus. Synonym: fasciculus mamillothalamicus, fasciculus thalamomamillaris, mamillothalamic tract, Vicq d'Azyr's bundle. (05 Mar 2000) |