Lateral corticospinal tract

The lateral corticospinal tract is a descending neural pathway primarily concerned with motor function. There are separate lateral and anterior corticospinal tracts as fibres decussate at the cevicomedullary junction.

Gross anatomy

Central connections

Corticospinal fibres arise from neurons in the cerebral cortex. Most of these arise in the primary motor and pre-motor cortices. In the primary motor cortex, fibres arise specifically from Betz cells. The somatosensory and the nearby parietal cortices supply a small number of fibres. 

Course

Organised somatotopically, these fibres descend through subcortical white matter. Following descent through the anterior two-thirds of the posterior limb of the internal capsule, they pass through the ventral midbrain, specifically the central and lateral portions of the inner crus, and continue through the pons. In the medulla oblongata, corticospinal fibres collect into a discrete bundle. This bundle forms the pyramid.

The pyramid is a discrete triangular column on the ventral medulla oblongata next to the midline. This is why the corticospinal tract is also called the pyramidal tract. Within the pyramids, the majority (75-90%) of the corticospinal fibres decussate. This is where the lateral corticospinal tract separates from the anterior corticospinal tract.

Lateral corticospinal tract

The lateral corticospinal tract and descends along the lateral funicular and then lies anterolateral to the dorsal horn. The oval-shaped lateral tract is much larger than the anterior counterpart. The lateral tract however, also contains a small amount of neurons that have not decussated.

As it descends, the lateral corticospinal tract deviates to the dorsolateral surface of the spinal cord. At the same time, it diminishes in size. At approximately the fourth sacral level, it terminates entirely.

Related pathology

 


Spinal anatomy
Neuroanatomy
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Article Information

rID: 47482
Section: Anatomy
Synonyms or Alternate Spellings:

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