| lamina spiralis ossea | A double plate of bone winding spirally around the modiolus dividing the spiral canal of the cochlea incompletely into two, scala tympani and scala vestibuli; between the two plates of this lamina the fibres of the cochlear nerve reach the spiral organ (of Corti). Synonym: lamina spiralis ossea, spiral plate. (05 Mar 2000) |
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| lamina spiralis secundaria | A ridge on the outer wall of the first turn of the cochlea opposite the spiral lamina. Synonym: lamina spiralis secundaria, secondary spiral plate. (05 Mar 2000) |
| limbus laminae spiralis osseae | The border of the spiral lamina; the thickened periosteum covering the upper plate of the bony spiral lamina of the cochlea. Synonym: limbus laminae spiralis osseae. (05 Mar 2000) |
| linea spiralis | A rough line that separates the neck and shaft of the femur anteriorly; it passes downward and medially from the greater trochanter to the lesser trochanter and continues into the medial lip of the linea aspera. Synonym: linea intertrochanterica, linea spiralis, spiral line. (05 Mar 2000) |
| radix lateralis tractus optici | The larger division of the posterior end of the optic tract that terminates in the lateral geniculate body. Synonym: radix lateralis tractus optici. (05 Mar 2000) |
| radix medialis tractus optici | 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) |
| rami tractus optici | The optic tract branches, branches of the anterior choroid artery to the optic tract. (05 Mar 2000) |
| nucleus tractus mesencephali nervi trigemini | <anatomy, nerve> A long, narrow plate of unipolar neurons extending throughout the length of the midbrain, in and along the lateral angle of the central gray substance. The nucleus is the single known instance of primary sensory neurons enclosed in the central nervous system instead of in a peripheral sensory ganglion. Its peripheral axonal processes pass with the trigeminal nerve, give collaterals to the trigeminal motor nucleus, and terminate in the muscles of mastication. Synonym: nucleus tractus mesencephali nervi trigemini. (05 Mar 2000) |
| nucleus tractus solitarii | A slender cell column extending sagittally through the dorsal part of the medulla oblongata, beneath the floor of the rhomboid fossa, immediately lateral to the limiting sulcus. It is the visceral sensory (visceral afferent) nucleus of the brainstem, receiving the afferent fibres of the vagus, glossopharyngeal, and facial nerves by way of the solitary tract. The caudal two-thirds of the nucleus processes impulses originating in the pharynx, larynx, intestinal and respiratory tracts, and heart and large blood vessels; its rostral one-third receives impulses from the taste buds and is known as the rhombencephalic gustatory nucleus. Synonym: nucleus tractus solitarii. (05 Mar 2000) |
| nucleus tractus spinalis nervi trigemini | The long sensory nucleus extending from the caudal border of the pontine sensory nucleus of the trigeminus down through the lateral region of the rhombencephalon into the upper three segments of the spinal cord's dorsal horn; it receives the fibres of the sensory root of the trigeminal nerve which descend along its lateral border as the spinal tract of trigeminal nerve. Synonym: nucleus tractus spinalis nervi trigemini, descending nucleus of the trigeminus, spinal nucleus of the trigeminus. (05 Mar 2000) |
| tractus | Synonym: tract. Origin: L. A drawing, drawing out, extent, tract, fr. Traho, pp. Tractus, to draw (05 Mar 2000) |
| tractus centralis tegmenti | 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) |
| tractus cerebellorubralis | 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) |
| tractus cerebellothalamicus | 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) |
| tractus corticobulbaris | <physiology> Collective term for those fibres (corticonuclear fibres) which separate from the corticospinal tract in the course of the latter's descent through the pons and medulla oblongata. Fibres of this tract innervate the motor nuclei of the trigeminal, facial, and hypoglossal nerves (perhaps also the nucleus ambiguus), directly and by way of interneurons in the lateral part of the rhombencephalic tegmentum. No direct supranuclear cortical innervation of the motor nuclei innervating the external eye muscles (oculomotor, trochlear, abducens) has been identified. Fibres of the corticobulbar tract also project into the formatio reticularis (i.e., corticoreticular fibres) and terminate upon sensory relay nuclei (e.g., gracile and cuneate nuclei, nucleus spinalis trigeminalis and nucleus solitarius). Synonym: tractus corticobulbaris. (05 Mar 2000) |