pyramidal tract


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Related to pyramidal tract: pyramidal tract signs

py·ram·i·dal tract

[TA]
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.

pyramidal tract

n.
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.

pyramidal tract

a pathway composed of groups of nerve fibers in the white matter of the spinal cord through which motor impulses are conducted to the anterior horn cells from the opposite side of the brain. These descending fibers, the nerve cell bodies of which are found in the precentral cortex, regulate the voluntary and reflex activity of the muscles through the anterior horn cells.

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.

pyramidal tract

The 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.
References in periodicals archive ?
3) It should also be remembered that "the great toe sign," or the Babinski reflex, does not mean a disturbance of the pyramidal tract itself, as usually thought, because this reflex could be present in patients with pure peripheral neuropathies, such as the Guillain-Barre syndrome, as well.
19] Other neurological manifestations include pyramidal tract signs, sensory deficits, involuntary movements and cerebellar ataxia.
The fascicular axons of the 6th nerve leave the nucleus and travel through the pontine tegmentum in an anterior and caudal direction, intersecting descending cortico-spinal axons of the pyramidal tract, before emerging at the junction between the pons and medulla, immediately lateral to the pyramidal axon bundles.