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The corticospinal tract is a white matter motor pathway starting at the cerebral cortex that terminates on lower motor neurons and interneurons in the spinal cord, controlling movements of the limbs and trunk. [1] There are more than one million neurons in the corticospinal tract, and they become myelinated usually in the first two years of life.
Descending tracts are pathways by which motor signals are sent from upper motor neurons in the brain to lower motor neurons which then directly innervate muscle to produce movement. The anterior corticospinal tract is usually small, varying inversely in size with the lateral corticospinal tract, which is the main part of the corticospinal tract.
The lateral corticospinal tract is a descending motor pathway that begins in the cerebral cortex, decussates in the pyramids of the lower medulla [1] (also known as the medulla oblongata or the cervicomedullary junction, which is the most posterior division of the brain [2]) and proceeds down the contralateral side of the spinal cord.
The pyramidal tracts include both the corticobulbar tract and the corticospinal tract.These are aggregations of efferent nerve fibers from the upper motor neurons that travel from the cerebral cortex and terminate either in the brainstem (corticobulbar) or spinal cord (corticospinal) and are involved in the control of motor functions of the body.
The pyramidal tracts (corticospinal tract and corticobulbar tracts) may directly innervate motor neurons of the spinal cord or brainstem (anterior (ventral) horn cells or certain cranial nerve nuclei), whereas the extrapyramidal system centers on the modulation and regulation (indirect control) of anterior (ventral) horn cells.
Tract Pathway Function corticospinal tract: from the motor cortex to lower motor neurons in the ventral horn of the spinal cord: The major function of this pathway is fine voluntary motor control of the limbs. The pathway also controls voluntary body posture adjustments. corticobulbar tract
The corticospinal tracts are on the anterior surface of the pyramids. These tracts transport motor signals that originated in the precentral gyrus and travelled through the internal capsule to the medulla oblongata and pyramids. Extrapyramidal tracts are those motor tracts that do not traverse the medullary pyramids.
Anterolateral corticospinal tract is a subdivision of the corticospinal tract in the spinal cord. It is formed by approximately 2% of the corticospinal fibers that do not cross to the opposite side of the brainstem in the pyramidal decussation. This tract descends in the lateral white column anterior to the lateral corticospinal tract. [1]