Corticobulbar tract

Cerebro: Corticobulbar tract File:Brain bulbar region.svg Components and location of the corticobulbar tract. [[Imagen:|250Px|centro|]] Latin tractus corticonuclearis Gray's subject # Part of Components Artery Vein BrainInfo/UW ancil-371 MeSH [1] The corticobulbar (or corticonuclear) tract is a white matter pathway connecting the cerebral cortex to the brainstem. Contenido 1 Anatomy 2 Función 3 Ver también 4 External links Anatomy The corticobulbar tract originates in motor cortex of the frontal lobe, just superior to the lateral fissure and rostral to the central sulcus. The tract descends through the genu of the internal capsule and a few fibers in the posterior limb of the internal capsule, as it passes from the cortex down to the midbrain. In the midbrain, the internal capsule becomes the cerebral peduncles. The white matter is located in the ventral portion of the cerebral peduncles, called the crus cerebri. The middle third of the crus cerebri contains the corticobulbar and corticospinal fibers. The corticobulbar fibers exit at the appropriate level of the brainstem to synapse on the lower motor neurons of the cranial nerves. Function The corticobulbar tract is composed of the upper motor neurons of the cranial nerves. The muscles of the face, head and neck are controlled by the corticobulbar system, which terminates on motor neurons within brainstem motor nuclei. This is in contrast to the corticospinal tract in which the cerebral cortex connects to spinal motor neurons, and thereby controls movement of the torso, upper and lower limbs. The corticobulbar tract innervates cranial motor nuclei bilaterally with the exception of the lower facial nuclei which are innervated only unilaterally (below the eyes) and cranial nerve XII which is innervated unilaterally as well. Both the lower part of cranial nerve VII and XII are innervated by the contralateral cortex. Among those nuclei that are bilaterally innervated a slightly stronger connection contralaterally than ipsilaterally is observed. The corticobulbar tract directly innervates the nuclei for cranial nerves V, VII, XI, and XII. It does not innervate nuclei for nerves III, IV, and VI because these are mediated by cortical projections and yoked together by the MLF, medial longitudinal fasciculus. The corticobulbar tract also contributes to the motor regions of nerves IX and X in the nucleus ambiguus. See also Upper motor neuron Upper motor neuron lesion External links Brainstem at UWisc 07CNXII Mesencephalon (midbrain) cerebral peduncle: midbrain tegmentum (periaqueductal gray, ventral tegmentum, nucleus raphe dorsalis), pretectum, substantia nigra, red nucleus, pedunculopontine nucleus, medial longitudinal fasciculus, medial lemniscus, rubrospinal tract, lateral lemniscus tectum: corpora quadrigemina, inferior colliculi, superior colliculi cerebral aqueduct: oculomotor nucleus, trochlear nucleus, Edinger-Westphal nucleus v·d·e Human brain, rhombencephalon, metencephalon: pons (TA A14.1.05.101-604, Georgia 9.785) Dorsal/ (tegmentum) Surface Cerebellopontine angle · Superior medullary velum · Sulcus limitans · Medial eminence · Facial colliculus White: Sensory/ascending Trapezoid body/VIII · Trigeminal lemniscus (Dorsal trigeminal tract, Ventral trigeminal tract) · Medial lemniscus · Lateral lemniscus MLF, III, IV and VI: Vestibulo-oculomotor fibers Anterior trigeminothalamic tract · Central tegmental tract White: Motor/descending ICP (Vestibulocerebellar tract) MLF, III, IV and VI: Vestibulospinal tract (Medial vestibulospinal tract, Lateral vestibulospinal tract) Grey: Cranial nuclei afferent: GSA: Principal V/Spinal V · VIII-c (Dorsal, Anterior)/VIII-v (Superior) efferent: SVE: Motor V · VII · GSE: VI · GVE: VII: Superior salivary nucleus Other grey Apneustic center · Pneumotaxic center (Medial parabrachial nucleus) · Lateral parabrachial nucleus · Superior olivary nucleus · Caerulean nucleus Ventral/ (base) Grey Pontine nuclei White: Motor/descending Corticospinal tract · Corticobulbar tract · Corticopontine fibers MCP (Pontocerebellar fibers) Surface Basilar sulcus Other grey: Raphe/ reticular Reticular formation (Caudal, Oral, Tegmental, Paramedian) · Raphe nuclei (Median) v·d·e Brain and spinal cord: neural tracts and fasciculi Sensory/ ascending PCML 1°: Pacinian corpuscle/Meissner's corpuscle → Gracile fasciculus/Cuneate fasciculus → Gracile nucleus/Cuneate nucleus 2°: → sensory decussation/arcuate fibers (Posterior external arcuate fibers, Internal arcuate fibers) → Medial lemniscus/Trigeminal lemniscus → Thalamus (VPL, VPM) 3°: → Posterior limb of internal capsule → Postcentral gyrus Anterolateral/ pain Fast/lateral 1° (Free nerve ending → A delta fiber) → 2° (Anterior white commissure → Lateral and Anterior Spinothalamic tract → Spinal lemniscus → VPL of Thalamus) → 3° (Postcentral gyrus) → 4° (Posterior parietal cortex) 2° (Spinotectal tract → Superior colliculus of Midbrain tectum) Slow/medial 1° (Group C nerve fiber → Spinoreticular tract → Reticular formation) → 2° (MD of Thalamus) → 3° (Cingulate cortex) Motor/ descending Pyramidal flexion: Primary motor cortex → Posterior limb of internal capsule → Decussation of pyramids → Corticospinal tract (Lateral, Anterior) → Neuromuscular junction Extrapyramidal flexion: Primary motor cortex → Genu of internal capsule → Corticobulbar tract → Facial motor nucleus → Facial muscles flexion: Red nucleus → Rubrospinal tract extension: Vestibulocerebellum → Vestibular nuclei → Vestibulospinal tract extension: Vestibulocerebellum → Reticular formation → Reticulospinal tract Midbrain tectum → Tectospinal tract → muscles of neck Basal ganglia direct: 1° (Motor cortex → Striatum) → 2° (GPi) → 3° (Lenticular fasciculus/Ansa lenticularis → Thalamic fasciculus → VL of Thalamus) → 4° (Thalamocortical radiations → Supplementary motor area) → 5° (Motor cortex) indirect: 1° (Motor cortex → Striatum) → 2° (GPe) → 3° (Subthalamic fasciculus → Subthalamic nucleus) → 4° (Subthalamic fasciculus → GPi) → 5° (Lenticular fasciculus/Ansa lenticularis → Thalamic fasciculus → VL of Thalamus) → 6° (Thalamocortical radiations → Supplementary motor area) → 7° (Motor cortex) nigrostriatal pathway: Pars compacta → Striatum Cerebellar Afferent Vestibular nucleus → Vestibulocerebellar tract → ICP → Cerebellum → Granule cell Pontine nuclei → Pontocerebellar fibers → MCP → Deep cerebellar nuclei → Granule cell Inferior olivary nucleus → Olivocerebellar tract → ICP → Hemisphere → Purkinje cell → Deep cerebellar nuclei Efferent Dentate nucleus in Lateral hemisphere/pontocerebellum → SCP → Dentatothalamic tract → Thalamus (VL) → Motor cortex Interposed nucleus in Intermediate hemisphere/spinocerebellum → SCP → Reticular formation, or → Cerebellothalamic tract → Red nucleus → Thalamus (VL) → Motor cortex Fastigial nucleus in Flocculonodular lobe/vestibulocerebellum → Vestibulocerebellar tract → Vestibular nucleus Bidirectional: Spinocerebellar Unc. prop. lower limb → 1° (muscle spindles → DRG) → 2° (Posterior thoracic nucleus → Dorsal/posterior spinocerebellar tract → ICP → Cerebellar vermis) upper limb → 1° (muscle spindles → DRG) → 2° (Accessory cuneate nucleus → Cuneocerebellar tract → ICP → Anterior lobe of cerebellum) Reflex arc lower limb → 1° (Golgi tendon organ) → 2° (Ventral/anterior spinocerebellar tract→ SCP → Cerebellar vermis) upper limb → 1° (Golgi tendon organ) → 2° (Rostral spinocerebellar tract → ICP → Cerebellum) {| clase="navbox plegable nowraplinks" estilo="margen:auto; " [. v]·[. d]·[. e] M: CNS anat (n/s/m/p/4/e/b/d/c/a/f/l/g)/phys/devp noco (m/d/e/h/v/s)/cong/tumr, sysi/epon, injr proc, droga (N1A/2AB/C/3/4/7A/B/C/D) [. v]·[. d]·[. e] M: PNS anat(h/r/t/c/b/l/s/a)/phys(r)/devp/prot/nttr/nttm/ntrp noco/auto/cong/tumr, sysi/epon, injr proc, droga(N1B) |} Esta página utiliza contenido con licencia Creative Commons de Wikipedia (ver autores).

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