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Related to pyramidal tract: pyramidal tract signs
an imprecisely defined term, generally used to describe axons from the cerebral cortex that enter the pyramid thereby representing all corticospinal fibers rostral to the pyramidal decussation; when the term is used to describe the lateral corticospinal tract, this entity should be designated as the crossed pyramidal tract. See: corticospinal tract.
Farlex Partner Medical Dictionary © Farlex 2012
A major pathway of the central nervous system, originating in the sensorimotor areas of the cerebral cortex and generally descending through the brainstem to the spinal cord. The fibers of the pyramidal tract transmit motor impulses that control voluntary movement.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.
py·ram·i·dal tract(pir-am'i-dăl trakt) [TA]
A massive bundle of fibers originating from pyramidal cells in the precentral motor and premotor area and in the postcentral gyrus. Fibers 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 fibers cross to the opposite side in the pyramidal decussation and descend in the spinal cord as the lateral pyramidal tract, which distributes its fibers to interneurons of the spinal gray matter. 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 and characterized by muscular weakness, spasticity and hyperreflexia, and a loss of discrete finger and hand movements. Babinski sign is associated with this condition of hemiplegia.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012
pyramidal tractThe great inverted pyramid of motor nerve fibres descending from the motor cortex of the cerebrum through the internal capsule and down into the brainstem where the fibre bundles on each side cross to the other side. This is why a STROKE on the right side causes paralysis on the left side of the body.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005