| respiratory tract | The air passages from the nose to the pulmonary alveoli, through the pharynx, larynx, trachea, and bronchi. (05 Mar 2000) |
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| 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) |
| cerebellorubral tract | That component of the superior cerebellar peduncle (brachium conjunctivum) which distributes fibres within the red nucleus of the opposite side. Synonym: tractus cerebellorubralis. (05 Mar 2000) |
| cerebellothalamic tract | That component of the superior cerebellar peduncle (brachium conjunctivum) which originates in the cerebellar nuclei, crosses completely in the decussation of the brachia conjunctiva, bypasses the red nucleus, and terminates in parts of the ventral anterior, ventral intermediate, ventral posterolateral, and central lateral nuclei of the thalamus. Synonym: tractus cerebellothalamicus, dentatothalamic tract. (05 Mar 2000) |
| reticulospinal tract | Collective term denoting a variety of fibre tracts descending to the spinal cord from the reticular formation of the pons and medulla oblongata. Part of these fibres conduct impulses from the neural mechanisms regulating autonomic functions to the corresponding somatic and visceral motor neurons of the spinal cord; others form links in nonpyramidal motor mechanisms affecting muscle tonus, reflex activity, and somatic movement. Synonym: tractus reticulospinalis. (05 Mar 2000) |
| Gowers' 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) |
| mesencephalic tract of trigeminal nerve | <anatomy, nerve> Located alongside the central substance of the midbrain and composed of primary sensory fibres, the cells of origin of which compose the mesencephalic nucleus of the trigeminus. Synonym: tractus mesencephalicus nervi trigemini. (05 Mar 2000) |
| granuloma, respiratory tract | Granulomatous diseases affecting one or more sites in the respiratory tract. (12 Dec 1998) |
| roots of olfactory tract | Lateral and medial, the two fibre bands that form the caudal continuation of the olfactory tract which, upon diverging, enclose the olfactory tubercle. (05 Mar 2000) |
| rubrobulbar tract | That component of the rubrospinal tract which distributes its fibres to lateral parts of the rhombencephalic tegmentum rather than the spinal cord, uncrossed rubro-olivary fibres. (05 Mar 2000) |
| rubroreticular tract | Fibres that pass from the red nucleus to the reticular formation of the pons and medulla. (05 Mar 2000) |
| rubrospinal tract | A somatotopically organised fibre bundle, relatively small in humans, arising from the red nucleus, immediately crossing in the ventral tegmental decussation, descending near the lateral surface of the brainstem into the lateral funiculus of the spinal cord at the ventral border of the lateral pyramidal tract. It terminates in the zona intermedia of the spinal cord where its distribution coincides with that of the lateral pyramidal tract; in contrast to the latter it appears not to have direct connections with spinal motor neurons. Impulses conveyed by this tract indirectly increase flexor muscle tone. Synonym: tractus rubrospinalis, Monakow's bundle, Monakow's tract, prepyramidal tract. (05 Mar 2000) |
| Waldeyer's tract | 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) |
| Monakow's tract | A somatotopically organised fibre bundle, relatively small in humans, arising from the red nucleus, immediately crossing in the ventral tegmental decussation, descending near the lateral surface of the brainstem into the lateral funiculus of the spinal cord at the ventral border of the lateral pyramidal tract. It terminates in the zona intermedia of the spinal cord where its distribution coincides with that of the lateral pyramidal tract; in contrast to the latter it appears not to have direct connections with spinal motor neurons. Impulses conveyed by this tract indirectly increase flexor muscle tone. Synonym: tractus rubrospinalis, Monakow's bundle, Monakow's tract, prepyramidal tract. (05 Mar 2000) |
| Collier's tract | A longitudinal bundle of fibres extending from the upper border of the mesencephalon into the cervical segments of the spinal cord, located close to the midline and ventral to the central gray matter; it is composed largely of fibres from the vestibular nuclei ascending to the motor neurons innervating the external eye muscles (abducens, trochlear, and oculomotor nuclei), and descending to spinal cord segments innervating the musculature of the neck. Synonym: fasciculus longitudinalis medialis, Collier's tract, medial longitudinal bundle, posterior longitudinal bundle. (05 Mar 2000) |