corticospinal tract

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cor·ti·co·spi·nal tract

a 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.

corticospinal tract

any of two groups of nerve fibers (the anterior corticospinal tract and lateral corticospinal tract) that originate in the cerebral cortex and run through the spinal cord. They are responsible for carrying motor fibers.

Corticospinal tract

A tract of nerve cells that carries motor commands from the brain to the spinal cord.
Mentioned in: Neurologic Exam

corticospinal tract

primary motor pathway descending from motor cortex to brainstem (where it decussates) and thence to the spinal cord, subserving contralateral voluntary motor control; injuries to the corticospinal tract show characteristics of an upper motor neurone lesion
References in periodicals archive ?
Clinicotopographical correlation of corticospinal tract stroke: A color-coded diffusion tensor imaging study.
Lesion load of the corticospinal tract predicts motor impairment in chronic stroke.
Functional potential in chronic stroke patients depends on corticospinal tract integrity.
Larger prospective studies that include more sensitive measures of corticospinal tract dysfunction than the EDSS, coupled with advanced neuroimaging techniques and, ideally, histopathological investigations, will help detect differences in the pattern and rate of RNFL loss by disease subtype and ON history, pointing to underlying pathological mechanisms of neurodegeneration [3,34].
In summary, we found RNFLt to correlate with disease duration in parallel with corticospinal tract dysfunction, as measured by the EDSS in a population with MS untreated by DMTs.
This is the first time that such extensive collateral growth in the corticospinal tract has been reported.
The corticospinal tract, whose axons originate far up in the motor cortex of the brain and then descend down the length of the spine, controls almost all motor function in the human body.
The corticospinal tract carries signals from the highest centers of the cerebral cortex that program voluntary movement down to the nerve cells in the spinal cord that activate the muscles of the fingers, hands, legs and feet.
With time, the integrity of the crus cerebri and its descending corticospinal tracts is disturbed, and a contralateral motor deficit is produced with a deteriorating level of consciousness.