Lexic.us

Definition of Corticospinal tract

1. Noun. 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 cord.

Medical Definition of Corticospinal tract

1. A massive bundle of fibres originating 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 postcentral gyrus. Cells of origin in area 4 include the gigantopyramidal cells of Betz. Fibres from these cortical regions descend through the internal capsule, the middle third of the crus cerebri, and the ventral part of the pons to emerge on the ventral surface of the medulla oblongata as the pyramis. Continuing caudally, most of the fibres cross to the opposite side in the pyramidal decussation and descend in the dorsal half of the lateral funiculus of the spinal cord as the lateral pyramidal tract, which distributes its fibres 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, fibres also pass directly to motoneuronal groups that innervate distal extremity muscles subserving particular hand-and-finger or foot-and-toe movements. The uncrossed fibres form a small bundle, the anterior pyramidal 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 the pyramidal tract at or below its cortical origin causes impairment of movement in the opposite body-half, especially severe in the arm and leg; characterised by muscular weakness, spasticity and hyperreflexia, and a loss of discrete finger and hand movements. Babinski's sign is associated with this condition of hemiplegia. Synonym: tractus corticospinalis, tractus pyramidalis, corticospinal tract. (05 Mar 2000)

Lexicographical Neighbors of Corticospinal Tract

Literary usage of Corticospinal tract

Below you will find example usage of this term as found in modern and/or classical literature:

1. The Anatomy of the Nervous System by Stephen Walter Ranson (1920)
"They end like those of the lateral corticospinal tract, either directly or ... An uncrossed ventral corticospinal tract seems to be present only in man and ..."

2. Journal of Nervous and Mental Disease by Philadelphia Neurological Society, American Neurological Association, Chicago Neurological Society, New York Neurological Association (1899)
"... and at the same time by involving the corticospinal tract to the sacral cord remove the cerebral inhibition from the Achilles reflex and thus allow the ..."

3. Journal of Nervous and Mental Disease by American Neurological Association, Philadelphia Neurological Society, Chicago Neurological Society, New York Neurological Association, Boston Society of Psychiatry and Neurology (1898)
"According to Van Gehuchten, the motor cortex is connected by two tracts with the cells of the peripheral motor fibres; by a direct corticospinal tract, ..."

4. Locomotor ataxia (tabes dorsalis): An Introduction to the Study and by William Joseph Marie Alois Maloney (1918)
""Descending" tracts: la, a fiber of the crossed pyramid or corticospinal tract; Ib, an uncrossed fiber of the pyramid or corticospinal tract passing to the ..."

5. The Medical Clinics of North America by Michael C. Fiore, Stephen S. Entman, Charles B. Rush (1922)
"Conspicuous degeneration of right corticospinal tract (above decussation). Case N-12-34: Age at death nineteen years. Duration of epilepsy seventeen years. ..."

6. Handbook of Severe Disability: A Text for Rehabilitation Counselors, Other edited by Walter C. Stolov, Michael R. Clowers (2000)
"Each nerve has two roots, the anterior, or ventral, motor root, and the Posterior horn corticospinal tract Spinothalamic tract White matter Middle cerebral ..."

7. Diseases of the nervous system: For the General Practitioner and Student by Alfred Gordon (1913)
"Spastic paralysis is due to a diseased condition of the corticospinal tract, especially the pyramidal tract. The latter carries two kinds of fibers: those ..."

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