Lateral corticospinal tract - wikipedia Lateral corticospinal tract Lateral corticospinal tract Lateral corticospinal tract labeled in red at upper left. Details Identifiers Latin Tractus corticospinalis lateralis, fasciculus cerebrospinalis lateralis Dorlands / Elsevier 12816937 TA A14. 1.02. 219 FMA 72635 Anatomical terminology ( edit on Wikidata ) 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. Contents 1 Structure 2 Function 3 Clinical significance 4 Additional images 5 References 6 External links Structure 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 ( also known as the medulla oblongata or the cervicomedullary junction, which is the most posterior division of the brain ) 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 Axons in the lateral corticospinal tract leave out of the tract and into 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. Damage to different parts of the body will cause deficits, depending on whether the damage is above ( rostral ) or below ( caudal ) the pyramidal decussation. Damage to the body above the pyramidal decussation will cause contralateral motor deficits. For example, if there is a lesion at the pre-central gyrus in the right cerebral cortex, then the left side of the body will be affected. Whereas damage below the pyramidal decussation will result in ipsilateral motor deficits. For example, spinal cord damage on the left side of the lateral corticospinal tract at the thoracic level can cause motor deficits to the left side of the body. Clinical significance This section does not cite any sources. Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed. ( December 2012 ) 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. Additional images Decussation of pyramids. Section of the medulla oblongata through the lower part of the decussation of the pyramids Section of the medulla oblongata at the level of the decussation of the pyramids. The motor tract. References This article incorporates text in the public domain from the 20th edition of Gray 's Anatomy ( 1918 ) Jump up ^ 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. Jump up ^ Pinel, John ( 2011 ). Biopsychology. Boston : Pearson Education Inc. ISBN 978 - 0 - 205 - 83256 - 9. Jump up ^ Blumenfeld, Neuroanatomy Through Clinical Cases, 2002 External links Wikimedia Commons has media related to Lateral corticospinal tract. hier - 798 at NeuroNames Overview at thebrain.mcgill.ca Illustration and text : sc97 / text / P4 / intro. htm at the University of Wisconsin - Madison Medical school Anatomy of the medulla Grey matter Cranial nuclei afferent : Solitary nucleus tract Dorsal respiratory group Gustatory nucleus Vestibular nuclei Lateral Medial Inferior efferent : Hypoglossal nucleus Nucleus ambiguus Dorsal nucleus of vagus nerve Inferior salivatory nucleus Dorsal Gracile nucleus Cuneate nucleus Accessory cuneate nucleus Ventral Ventral respiratory group Arcuate nucleus of medulla Rostral ventromedial medulla Botzinger complex Pre-Bötzinger complex White matter Dorsal Sensory Sensory decussation Medial lemniscus Juxtarestiform body Ascending dorsal longitudinal fasciculus Medial longitudinal fasciculus Motor Descending dorsal longitudinal fasciculus Medial longitudinal fasciculus Ventral Descending tracts Olivocerebellar tract Rubro - olivary tract Surface Front Pyramid Anterior median fissure Anterolateral sulcus Olive Inferior olivary nucleus Back Posterior median sulcus Posterolateral sulcus Area postrema Vagal trigone Hypoglossal trigone Medial eminence Inferior cerebellar peduncle Grey Reticular formation Gigantocellular Parvocellular Ventral Lateral Paramedian Raphe nuclei Obscurus Magnus Pallidus Perihypoglossal nuclei The spinal cord General features Cervical enlargement Lumbar enlargement Conus medullaris Filum terminale Cauda equina Meninges Grey matter Posterior grey column Marginal nucleus Substantia gelatinosa of Rolando Nucleus proprius Spinal lamina V Spinal lamina VI Lateral grey column Intermediolateral nucleus Posterior thoracic nucleus Anterior grey column Interneuron Alpha motor neuron Onuf 's nucleus Gamma motor neuron Other Rexed laminae Central gelatinous substance Gray commissure Central canal Terminal ventricle White matter Sensory Posterior Posterior column - medial lemniscus pathway : Gracile Cuneate Lateral : Spinocerebellar dorsal ventral Spinothalamic lateral anterior Posterolateral Spinotectal Spinoreticular tract Spino - olivary tract Motor Lateral Corticospinal Lateral Extrapyramidal Rubrospinal Olivospinal Raphespinal Anterior Corticospinal Anterior Extrapyramidal Vestibulospinal Reticulospinal Tectospinal Both Anterior white commissure External features Ventral Anterior median fissure Anterolateral sulcus Dorsal Posterior median sulcus Posterolateral sulcus Brain and spinal cord : neural tracts and fasciculi Sensory / ascending PCML 1 ° : Pacinian corpuscle / Meissner 's corpuscle → Posterior column ( Gracile fasciculus / Cuneate fasciculus ) → Gracile nucleus / Cuneate nucleus 2 ° : → sensory decussation / arcuate fibers ( Posterior external arcuate fibers, Internal arcuate fibers ) → Medial lemniscus / Trigeminal lemniscus → Thalamus ( VPL, VPM ) 3 ° : → Posterior limb of internal capsule → Postcentral gyrus Anterolateral / pain Fast / lateral 1 ° ( Free nerve ending → A delta fiber ) → 2 ° ( Anterior white commissure → Lateral and Anterior Spinothalamic tract → Spinal lemniscus → VPL of Thalamus ) → 3 ° ( Postcentral gyrus ) → 4 ° ( Posterior parietal cortex ) 2 ° ( Spinomesencephalic tract → Superior colliculus of Midbrain tectum ) Slow / medial 1 ° ( Group C nerve fiber → Spinoreticular tract → Reticular formation ) → 2 ° ( MD of Thalamus ) → 3 ° ( Cingulate cortex ) Motor / descending Pyramidal flexion : Primary motor cortex → Posterior limb of internal capsule → Decussation of pyramids → Corticospinal tract ( Lateral, Anterior ) → Neuromuscular junction Extrapyramidal flexion : Primary motor cortex → Genu of internal capsule → Corticobulbar tract → Facial motor nucleus → Facial muscles flexion : Red nucleus → Rubrospinal tract extension : Vestibulocerebellum → Vestibular nuclei → Vestibulospinal tract extension : Vestibulocerebellum → Reticular formation → Reticulospinal tract Midbrain tectum → Tectospinal tract → muscles of neck Basal ganglia direct : 1 ° ( Motor cortex → Striatum ) → 2 ° ( GPi ) → 3 ° ( Lenticular fasciculus / Ansa lenticularis → Thalamic fasciculus → VL of Thalamus ) → 4 ° ( Thalamocortical radiations → Supplementary motor area ) → 5 ° ( Motor cortex ) indirect : 1 ° ( Motor cortex → Striatum ) → 2 ° ( GPe ) → 3 ° ( Subthalamic fasciculus → Subthalamic nucleus ) → 4 ° ( Subthalamic fasciculus → GPi ) → 5 ° ( Lenticular fasciculus / Ansa lenticularis → Thalamic fasciculus → VL of Thalamus ) → 6 ° ( Thalamocortical radiations → Supplementary motor area ) → 7 ° ( Motor cortex ) nigrostriatal pathway : Pars compacta → Striatum Cerebellar Afferent Vestibular nuclei → Vestibulocerebellar tract → ICP → Cerebellum → Granule cell Pontine nuclei → Pontocerebellar fibers → MCP → Deep cerebellar nuclei → Granule cell Inferior olivary nucleus → Olivocerebellar tract → ICP → Hemisphere → Purkinje cell → Deep cerebellar nuclei Efferent Dentate nucleus in Lateral hemisphere / pontocerebellum → SCP → Dentatothalamic tract → Thalamus ( VL ) → Motor cortex Interposed nucleus in Intermediate hemisphere / spinocerebellum → SCP → Reticular formation, or → Cerebellothalamic tract → Red nucleus → Thalamus ( VL ) → Motor cortex Fastigial nucleus in Flocculonodular lobe / vestibulocerebellum → Vestibulocerebellar tract → Vestibular nuclei Bidirectional : Spinocerebellar Unconscious proprioception lower limb → 1 ° ( muscle spindles → DRG ) → 2 ° ( Posterior thoracic nucleus → Dorsal / posterior spinocerebellar tract → ICP → Cerebellar vermis ) upper limb → 1 ° ( muscle spindles → DRG ) → 2 ° ( Accessory cuneate nucleus → Cuneocerebellar tract → ICP → Anterior lobe of cerebellum ) Reflex arc lower limb → 1 ° ( Golgi tendon organ ) → 2 ° ( Ventral / anterior spinocerebellar tract → SCP → Cerebellar vermis ) upper limb → 1 ° ( Golgi tendon organ ) → 2 ° ( Rostral spinocerebellar tract → ICP → Cerebellum ) Retrieved from `` https://en.wikipedia.org/w/index.php?title=Lateral_corticospinal_tract&oldid=779070859 '' Categories : Wikipedia articles incorporating text from the 20th edition of Gray 's Anatomy ( 1918 ) Motor system Spinal cord tracts Hidden categories : Medicine infobox template using GraySubject or GrayPage Medicine infobox template using Dorlands parameter Articles needing additional references from December 2012 All articles needing additional references Talk Contents About Wikipedia Português Edit links This page was last edited on 6 May 2017, at 21 : 34. 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Question: where are descending tracts found in the spinal cord
Answer: lateral corticospinal tract