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The corticospinal tract originates in several parts of the brain, including not just the motor areas, but also the primary somatosensory cortex and premotor areas. [1] Most of the neurons originate in either the primary motor cortex (precentral gyrus, Brodmann area 4) or the premotor frontal areas.
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 lateral corticospinal tract (also called the crossed pyramidal tract or lateral cerebrospinal fasciculus) is the largest part of the corticospinal tract.It extends throughout the entire length of the spinal cord, and on transverse section appears as an oval area in front of the posterior column and medial to the posterior spinocerebellar tract.
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. It lies close to the anterior median fissure , and is present only in the upper part of the spinal cord; gradually diminishing in size as it descends, it ends about the middle of ...
Having crossed over at the middle line, they pass down in the posterior part of the lateral funiculus as the lateral corticospinal tract. The other 10% of the fibers stay uncrossed in the anterior corticospinal tract. The pyramidal decussation marks the border between the spinal cord and the medulla oblongata. [1]
Normal motor control depends on the development of connections between the axons in the corticospinal tract and the spinal cord. Pyramidal cell axons follow cues such as growth factors to make specific connections. With proper connections, pyramidal cells take part in the circuitry responsible for vision guided motor function. [20]
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 corticobulbar and corticospinal fibers are found in the middle third of the cerebral peduncle. [7] The corticospinal tract exits the internal capsule and is seen in the mid portion of the cerebral peduncles.