| 释义 |
corticospinal tract
Thesaurus| Noun | 1. |  corticospinal tract - any of the important motor nerves on each side of the central nervous system that run from the sensorimotor areas of the cortex through the brainstem to motor neurons of the cranial nerve nuclei and the ventral root of the spinal cordpyramidal motor system, pyramidal tractefferent, efferent nerve, motor nerve - a nerve that conveys impulses toward or to muscles or glandscentral nervous system, CNS, systema nervosum centrale - the portion of the vertebrate nervous system consisting of the brain and spinal cordbasal ganglion - any of several masses of subcortical grey matter at the base of each cerebral hemisphere that seem to be involved in the regulation of voluntary movement |
corticospinal tract
cor·ti·co·spi·nal tracta composite bundle of corticospinal fibers [TA] that descend into and through the medulla to form the lateral corticospinal tract [TA] and the anterior corticospinal tract [TA]. This massive bundle of fibers originates from pyramidal cells of various sizes in the fifth layer of the precentral motor (area 4), the premotor area (area 6), and to a lesser extent from the somatosensory cortex. Cells of origin in area 4 include the gigantopyramidal cells of Betz. Fibers from these cortical regions descend through the internal capsule, the middle third of the crus cerebri, and the basilar pons to emerge on the anterior surface of the medulla oblongata as the pyramid. Continuing caudally, most of the fibers cross to the opposite side in the pyramidal (motor) decussation and descend in the posterior half of the lateral funiculus of the spinal cord as the lateral corticospinal tract, which distributes its fibers throughout the length of the spinal cord to interneurons of the zona intermedia of the spinal gray matter. In the (extremity-related) spinal cord enlargements, fibers also pass directly to motoneuronal groups that innervate distal extremity muscles subserving particular hand-and-finger or foot-and-toe movements. The uncrossed fibers form a small bundle, the anterior corticospinal tract, which descends in the anterior funiculus of the spinal cord and terminates in synaptic contact with interneurons in the medial half of the anterior horn on both sides of the spinal cord. Interruption of corticospinal fibers rostral to the motor (pyramidal) decussation causes impairment of movement in the opposite body-half, which is especially severe in the arm and leg and is characterized by muscular weakness, spasticity and hyperreflexia, and a loss of discrete finger and hand movements. Lesions of lateral corticospinal fibers caudal to the motor decussation result in comparable deficits on the ipsilateral side of the body. The Babinski sign is associated with this condition of hemiplegia. Synonym(s): tractus pyramidalis [TA], tractus corticospinalisCorticospinal tractA tract of nerve cells that carries motor commands from the brain to the spinal cord.Mentioned in: Neurologic ExamFinancialSeetractAcronymsSeeCSTcorticospinal tract
Related to corticospinal tract: Lateral corticospinal tract, Anterior corticospinal tractSynonyms for corticospinal tractnoun any of the important motor nerves on each side of the central nervous system that run from the sensorimotor areas of the cortex through the brainstem to motor neurons of the cranial nerve nuclei and the ventral root of the spinal cordSynonyms- pyramidal motor system
- pyramidal tract
Related Words- efferent
- efferent nerve
- motor nerve
- central nervous system
- CNS
- systema nervosum centrale
- basal ganglion
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