| mamillothalamic tract | 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) |
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| ventral spinocerebellar tract | A bundle of fibres originating in the base of the posterior horn and zona intermedia throughout lumbosacral segments of the spinal cord, crossing to the opposite side and ascending in a peripheral position in the ventral half of the lateral funiculus. In its ascent through the rhombencephalon, the tract curves sharply dorsalward along the rostral border of the trigeminal motor nucleus, entering the cerebellum in a caudal direction over the dorsal surface of the superior cerebellar peduncle, and terminating as mossy fibres in the granular layer of the cortex of the cerebellar vermis. The bundle conveys proprioceptive and exteroceptive information largely from the opposite lower extremity. Synonym: tractus spinocerebellaris anterior, Gowers' column, Gowers' tract, ventral spinocerebellar tract. (05 Mar 2000) |
| ventral spinothalamic tract | The more anterior or ventral part of the spinothalamic tract that is involved in tactile sensation. See: spinothalamic tract. Synonym: tractus spinothalamicus anterior, ventral spinothalamic tract. (05 Mar 2000) |
| Marchi's tract | A bundle of thick, heavily myelinated fibres originating in the deep layers of the superior colliculus, crossing to the opposite side in the dorsal tegmental decussation, descending along the median plane, between the medial longitudinal fasciculus dorsally, the medial lemniscus ventrally, into the anterior funiculus of the spinal cord. The tract ends in the medial region of the anterior horn of the cervical spinal cord, and appears to be involved in head movements during visual and auditory tracking. Throughout its course in the brainstem it is accompanied by fibres of the tectobulbar tract. Synonym: tractus tectospinalis, Held's bundle, Loewenthal's bundle, Loewenthal's tract, Marchi's tract, predorsal bundle. (05 Mar 2000) |
| geniculocalcarine tract | The massive, fanlike fibre system passing from the lateral geniculate body of the thalamus to the visual cortex (striate or calcarine cortex, area 17 of Brodmann); the fibres follow the retrolenticular and sublenticular limbs of the internal capsule into the corona radiata but they curve back along the lateral wall of the temporal and occipital horns of the lateral ventricle to the striate cortex on the medial surface and pole of the occipital lobe. Synonym: radiatio optica, geniculocalcarine radiation, geniculocalcarine tract, Gratiolet's fibres, Gratiolet's radiation, occipitothalamic radiation, Wernicke's radiation. (05 Mar 2000) |
| genital tract | The genital passages of the urogenital apparatus. Synonym: genital duct. (05 Mar 2000) |
| genitourinary tract | Includes the kidneys, ureters, bladder and urethra. (27 Sep 1997) |
| parietopontine tract | A system of fibres originating in the parietal lobe of the cerebral hemisphere which descend in the internal capsule and lateral part of the crus cerebri to terminate in the pontine nuclei or ventral part of the pons. Synonym: tractus parietopontinus. (05 Mar 2000) |
| vestibulospinal tract | A somatopically organised fibre bundle originating from the lateral vestibular nucleus (nucleus of Deiters) which descends uncrossed into the anterior funiculus of the spinal cord lateral to the anterior median fissure; the tractus extends throughout the length of the cord, distributing fibres at all levels to the medial part of the anterior horn. Excitatory impulses conveyed by the vestibulospinal tract increase extensor muscle tone. Synonym: tractus vestibulospinalis, deiterospinal tract. (05 Mar 2000) |
| GI-tract secretions | <radiology> Organ Volume (ml/day) ----- --------------- Salivary glands 1500 Stomach 2500 Biliary system 500 Pancreas 1500 Intestine 1000 (12 Dec 1998) |
| GI-tract target lesion | <radiology> Metastatic melanoma, primary neoplasm, spindle cell tumour (benign or malignant), lymphoma, carcinoid, carcinoma, metastasis, breast carcinoma, lung carcinoma, renal carcinoma, Kaposi's sarcoma, eosinophilic granuloma, ectopic pancreas (12 Dec 1998) |
| medial root of optic tract | The smaller division of the posterior end of the optic tract that disappears under the medial geniculate body. Synonym: radix medialis tractus optici. (05 Mar 2000) |
| central tegmental tract | A large fibre bundle passing longitudinally through the central mesencephalic and pontine tegmentum, distinguished from adjacent longitudinal groups of fibre-fascicles of the reticular formation by a more compact composition. In transverse sections of the mesencephalon the bundle occupies a large triangular area lateral to the medial longitudinal fasciculus; farther caudally it expands ventralward and finally passes over the lateral side of the (inferior) olivary nucleus, becoming part of the latter's fibre capsule. The bundle contains fibres from the mesencephalic tegmentum and regions surrounding the central gray substance descending to the olivary nucleus; it also includes numerous fibres ascending from the medullary, pontine, and mesencephalic reticular formation to the thalamus and subthalamus region. Synonym: tractus tegmentalis centralis, central tegmental fasciculus, tractus centralis tegmenti. (05 Mar 2000) |
| respiratory tract | The air passages from the nose to the pulmonary alveoli, through the pharynx, larynx, trachea, and bronchi. (05 Mar 2000) |
| respiratory tract fistula | An abnormal passage communicating between any parts of the respiratory tract or between any part of the respiratory system and other organs. (12 Dec 1998) |