| IH | idiopathic hirsutism; idiopathic hypercalciuria; immediate hypersensitivity; incompletely healed; in... |
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| IHC | idiopathic hemochromatosis; idiopathic hypercalciuria; immunohistochemistry; inner hair cell; intrah... |
| IM | idiopathic myelofibrosis; immunosuppressive method; implementation monitoring; Index Medicus; indome... |
| IOA | inner optic anlage; International Osteopathic Association |
| IPL | inner plexiform layer; intrapleural |
| mamillotegmental fasciculus | A small bundle of fibres that passes dorsalward from the mamillary body for a short distance with the mamillothalamic tract, then turns down the brainstem to reach the dorsal and ventral tegmental nuclei of the mesencephalon. Synonym: fasciculus mamillotegmentalis. (05 Mar 2000) |
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| mamillothalamic fasciculus | 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) |
| marginal fasciculus | 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) |
| medial longitudinal fasciculus | 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) |
| pedunculomamillary fasciculus | 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) |
| central tegmental fasciculus | 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) |
| retroflex fasciculus | 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) |
| gracile fasciculus | The smaller medial subdivision of the posterior funiculus. Synonym: fasciculus gracilis. (05 Mar 2000) |
| perpendicular fasciculus | A bundle of association fibres running vertically and interconnecting regions of the temporal, occipital, and parietal lobes. (05 Mar 2000) |
| Meynert's fasciculus | 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) |
| round fasciculus | 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) |
| wedge-shaped fasciculus | The larger lateral subdivision of the posterior funiculus. Synonym: fasciculus cuneatus, Burdach's column, Burdach's fasciculus, Burdach's tract, cuneate funiculus, wedge-shaped fasciculus. (05 Mar 2000) |
| cuneate fasciculus | The larger lateral subdivision of the posterior funiculus. Synonym: fasciculus cuneatus, Burdach's column, Burdach's fasciculus, Burdach's tract, cuneate funiculus, wedge-shaped fasciculus. (05 Mar 2000) |
| semilunar fasciculus | 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) |
| hooked fasciculus | A band of long association fibres reciprocally connecting the frontal and temporal lobes of the cerebrum, running caudally through the white matter of the frontal lobe, sharply curving ventrally under the stem of the sylvian fissure, and then fanning out to the cortex of the anterior half of the superior and middle temporal gyri. Synonym: fasciculus uncinatus, arcuate fasciculus, frontotemporal tract, hooked fasciculus, temporofrontal tract. (05 Mar 2000) |