Lateral corticospinal tract

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Lateral corticospinal tract
Spinal cord tracts - English.svg
Lateral corticospinal tract labeled in red at upper left.
Latin Tractus corticospinalis lateralis,
fasciculus cerebrospinalis lateralis
Gray's p.759
Dorlands
/Elsevier
12816937
Anatomical terminology

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 medulla spinalis, and on transverse section appears as an oval area in front of the posterior column and medial to the posterior spinocerebellar tract.

Structure[edit]

Descending motor pathways carry motor signals from the brain down the spinal cord and to the target muscle or organ. They typically consist of an upper motor neuron and a lower motor neuron. 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 myelencephalon, the most posterior division of the brain[2] ) and proceeds down the contralateral side of the spinal cord. It is the largest part of the corticospinal tract. It extends throughout the entire length of the medulla spinalis, and on transverse section appears as an oval area in front of the posterior column and medial to the posterior spinocerebellar tract.

Function[edit]

The lateral corticospinal tract leaves out of the anterior horns of the spinal cord. It controls fine movement of ipsilateral limbs (albeit contralateral to the corresponding motor cortex) as it lies distal to the pyramidal decussation. Control of more central axial and girdle muscles comes from the anterior corticospinal tract.[3]

Clinical significance[edit]

Poliomyelitis and amyotrophic lateral sclerosis arise out of complications in the lateral corticospinal tract. Both of these diseases result in muscle atrophy. In poliomyelitis, the poliovirus destroys motor neurons found in the brainstem and anterior horn of the spinal cord. This inhibits the lower motor neurons of the lateral corticospinal tract from travelling to the target muscle or organ and delivering the signal from the brain. In amyotrophic lateral sclerosis, the lateral side of the spinal cord undergoes scarring. The astrocytes found in the spinal cord, which are vital to the healthy functioning of the central nervous system, fail to reabsorb a specific neurotransmitter. This causes the neurotransmitter to reach toxic levels and leads to scarring in the lateral regions of the spinal cord. This also disrupts neural signal transmission.

References[edit]

This article incorporates text from a public domain edition of Gray's Anatomy.

  1. ^ Saladin, Kenneth (2012). Anatomy and Physiology: The Unity of Form and Function. New York: McGraw-Hill. pp. 486–488. ISBN 978-0-07-337825-1. 
  2. ^ Pinel, John (2011). Biopsychology. Boston: Pearson Education Inc. ISBN 978-0-205-83256-9. 
  3. ^ Blumenfeld, Neuroanatomy Through Clinical Cases, 2002

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