| Posterior thoracic nucleus |
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| Diagram showing a few of the connections of afferent (sensory) fibers of the posterior root with the efferent fibers from the ventral column and with the various long ascending fasciculi. (Dorsal nucleus labeled at center right.) |
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| Schematic of spinal cord grey matter showing location of the Dorsal Nucleus |
| Latin |
nucleus thoracicus posterior, nucleus dorsalis |
| Gray's |
subject #185 758 |
Clarke's column (column of Clarke, dorsal nucleus, posterior thoracic nucleus, nucleus dorsalis of Clarke) is a group of interneurons found in the medial part of Lamina VII, also known as the intermediate zone, of the spinal cord. It is mainly located from the T1 to L3-L4 levels and is an important structure for proprioception.
Contents
- 1 Anatomy
- 2 Function
- 3 Diseases
- 4 Eponym
- 5 References
- 6 External links
Anatomy[edit]
It occupies the medial part of the base of the posterior horn and appears on the transverse section as a well-defined oval area.
It begins caudally at the level of the second or third lumbar nerve, and reaches its maximum size opposite the twelfth thoracic nerve. Above the level of the eight thoracic nerve its size diminishes, and the column ends opposite the last cervical or first thoracic nerve.
It is represented, however, in the other regions by scattered cells, which become aggregated to form a cervical nucleus opposite the third cervical nerve, and a sacral nucleus in the middle and lower part of the sacral region.
Nerve cells in Clarke’s column are most abundant between the lower thoracic and upper lumbar segments. Cell bodies are of medium size and oval- or pyriform-shape. These cells characteristically present coarse Nissl granules and have characteristic eccentric nuclei. [1]
Axonal projections from neurons in this nucleus give rise to the dorsal spinocerebellar tract which ascends ipsilaterally through the spinal cord and ends as Mossy fibers in the ipsilateral cerebellar cortex after passing through the inferior cerebellar peduncle. [2] Axons originatig from the nucleus dorsalis which ascend contralaterally through the lateral funiculus of the spinal cord are named ventral spinocerebellar tract which cross over again whitin the brainstem to end on the ipsilateral side.
Function[edit]
Clarke’s column is a major relay center for unconscious proprioception. Sensory information from muscle spindles and tendon organs is carried by axons of larger neurons in posterior root ganglia, which synapse onto neurons in the spinal cord including cells in Clarke’s column. From Clarke’s column, information continues rostrally until it reaches the cerebellar cortex. This relay pathway is generally known as the dorsal spinocerebellar tract.
Diseases[edit]
It has been observed that in Friedreich's ataxia there is evident degeneration of the Dorsal Nucleus of Clarke as well as other propioceptive spinal tracts. These patients might present with ataxia, dysarthria, muscle weakness or paralysis and skeletal defects. [3]
Eponym[edit]
It is named for Jacob Augustus Lockhart Clarke.[4][5]
References[edit]
- ^ Carpenter, Malcolm (1991). Core text of Neuroanatomy. Baltimore, Maryland: Williams & Wilkins. p. 70. ISBN 0683014579.
- ^ Blumenfeld, Hal (2010). Neuroanatomy through Clinical Cases. MA: Sinauer. pp. 709–710. ISBN 9780878930586.
- ^ Haines, Duane (2008). Neuroanatomy an Atlas of Structures, Sections and Systems. PA: Lippincott Williams & Wilkins. pp. 222–223. ISBN 0781763282.
- ^ synd/2143 at Who Named It?
- ^ J. A. L. Clarke. Researches into the structure of the spinal cord. Philosophical Transactions of the Royal Society of London, 1851, 141: 607-621.
External links[edit]
- http://isc.temple.edu/neuroanatomy/lab/atlas/L3/
- http://www.neuroanatomy.wisc.edu/sc97/text/p3/Pathway.htm
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Anatomy of torso (primarily): the spinal cord (TA 14.1.02, GA 9.749)
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| External, dorsal |
Posterior median sulcus · Posterolateral sulcus
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Grey matter/
Rexed laminae |
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I–VI: Posterior horn
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I: Marginal nucleus · II: Substantia gelatinosa of Rolando · III+IV: Nucleus proprius · Spinal lamina V · Spinal lamina VI
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VII: Lateral horn
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Intermediolateral nucleus · Posterior thoracic nucleus
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VIII–IX: Anterior horn
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Interneuron · Alpha motor neuron (Onuf's nucleus)
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X: Other
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Central gelatinous substance · Gray commissure
Central canal · Terminal ventricle
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| White matter |
somatic/
ascending
(blue) |
Posterior/PCML: touch: Gracile · Cuneate
Lateral: proprioception: Spinocerebellar (Dorsal, Ventral) · pain/temp: Spinothalamic (Lateral, Anterior) · Posterolateral (Lissauer) · Spinotectal
Spinoreticular tract · Spino-olivary tract
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Lateral: Corticospinal (Lateral) · Ep (Rubrospinal, Olivospinal)
Anterior: Corticospinal (Anterior) · Ep (Vestibulospinal, Reticulospinal, Tectospinal)
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both
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Anterior white commissure
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| External, ventral |
Anterior median fissure · Anterolateral sulcus
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| External, general |
Cervical enlargement · Lumbar enlargement · Conus medullaris · Filum terminale · Cauda equina
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anat (n/s/m/p/4/e/b/d/c/a/f/l/g)/phys/devp
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noco (m/d/e/h/v/s)/cong/tumr, sysi/epon, injr
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proc, drug (N1A/2AB/C/3/4/7A/B/C/D)
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Brain and spinal cord: neural tracts and fasciculi
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Sensory/
ascending |
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PCML
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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
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Anterolateral/
pain
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Fast/lateral
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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° ( Spinotectal tract → Superior colliculus of Midbrain tectum)
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Slow/medial
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1° (Group C nerve fiber → Spinoreticular tract → Reticular formation) → 2° (MD of Thalamus) → 3° (Cingulate cortex)
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Motor/
descending |
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Pyramidal
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flexion: Primary motor cortex → Posterior limb of internal capsule → Decussation of pyramids → Corticospinal tract (Lateral, Anterior) → Neuromuscular junction
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Extrapyramidal
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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
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Basal ganglia
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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
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| Cerebellar |
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Afferent
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Vestibular nucleus → 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
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Efferent
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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 nucleus
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Bidirectional:
Spinocerebellar
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Unc. prop.
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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)
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Reflex arc
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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)
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anat (n/s/m/p/4/e/b/d/c/a/f/l/g)/phys/devp
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noco (m/d/e/h/v/s)/cong/tumr, sysi/epon, injr
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proc, drug (N1A/2AB/C/3/4/7A/B/C/D)
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anat (h/r/t/c/b/l/s/a)/phys (r)/devp/prot/nttr/nttm/ntrp
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noco/auto/cong/tumr, sysi/epon, injr
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