Column of Clarke

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Column of Clarke
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.)
Schematic of spinal cord grey matter showing location of the Dorsal Nucleus
Latin	nucleus thoracicus posterior, nucleus dorsalis
Gray's	subject #185 758
Dorlands/Elsevier	n_11/12583750

Clarke's column (column of Clarke, dorsal nucleus, posterior thoracic nucleus) is a group of interneurons found in Lamina VII, also known as the intermediate zone, of the spinal cord.

Contents 1 Anatomy 2 Function 3 Eponym 4 References 5 External links

[edit] Anatomy

It occupies the medial part of the base of the posterior column and appears on the transverse section as a well-defined oval area.

It begins below 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 ninth 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. Some cells can be as large as anterior horn cells; the nuclei of these larger cells are often found on the periphery of the cell.

[edit] Function

Clarke’s column is a major relay center for unconscious proprioception. Sensory information for muscle spindles and tendon organs synapses onto dorsal root ganglion, which in turn synapses onto Clarke’s column. From Clarke’s column, information continues rostrally until it reaches the cerebellar cortex. This relay pathway is generally known as the spinocerebellar tract.

[edit] Eponym

It is named for Jacob Augustus Lockhart Clarke.^[1][2]

[edit] References

[edit] External links

• http://isc.temple.edu/neuroanatomy/lab/atlas/L3/
• http://www.neuroanatomy.wisc.edu/sc97/text/p3/Pathway.htm

v • d • e Brain and spinal cord: neural tracts and fasciculi Sensory/ascending: PCML Pacinian corpuscle/Meissner's corpuscle → PCML → arcuate fibers (Posterior external arcuate fibers, Internal arcuate fibers) - Medial lemniscus → Thalamus → Postcentral gyrus Sensory/ascending: anterolateral system Free nerve ending → Spinothalamic tract (Lateral, Anterior) → Spinal lemniscus → Postcentral gyrus Spinoreticular tract → Reticular formation Spinotectal tract → Midbrain tectum Motor/descending: pyramidal and extrapyramidal flexion: Primary motor cortex → Posterior limb of internal capsule → Decussation of the pyramids → Corticospinal tract (Lateral, Anterior) → Neuromuscular junction flexion: Red nucleus → Rubrospinal tract extension: Vestibulocerebellum → Vestibular nuclei → Vestibulospinal tract extension: Vestibulocerebellum → Reticular formation → Reticulospinal tract Midbrain tectum → Tectospinal tract → muscles of neck Bidirectional: Spinocerebellar Unconscious proprioception: Golgi tendon organ → Spinocerebellar (Dorsal/Dorsal nucleus of Clarke/Column of Clarke, Cuneocerebellar) → Cerebellum Reflex arc: Ventral - Rostral Brain only Medial longitudinal fasciculus Vestibular nucleus → Vestibulocerebellar tract → Cerebellum Pontine nuclei → Pontocerebellar fibers → Deep cerebellar nuclei Inferior olivary nucleus → Olivocerebellar tract → Cerebellar hemisphere Primary motor cortex → Genu of internal capsule → Corticobulbar tract → brainstem see also white matter fibers