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The spinocerebellar tract is a set of axonal fibers originating in the spinal cord and terminating in the ipsilateral cerebellum. This tract conveys information to the cerebellum about limb and joint position (proprioception).

Origins of proprioceptive information

Proprioceptive information is obtained by Golgi tendon organs and muscle spindles.

Golgi tendon organs consist of a fibrous capsule enclosing tendon fascicles and bare nerve endings that respond to tension in the tendon by causing action potentials in Ib afferent neurons (relatively large, myelinated, quickly conducting).
Muscle spindles fibers are complicated systems of length monitoring within muscles which result in information being carried via Ia neurons (larger and faster than Ib) (from both nuclear bag fibers and nuclear chain fibers) and II neurons (solely from nuclear chain fibers).

All of these neurons are "first order" or "primary" and are sensory (and thus have their cell bodies in the dorsal root ganglion). They pass through Rexed laminae layers I-VI of the dorsal horn to form synapses with "second order" or "secondary" neurons in the layer just beneath the dorsal horn (layer VII).

Subdivisions of the tract

The tract is divided into:^[1]^{[dubious – discuss]}

Division	Peripheral Process of First Order the Neuron	Region of Innervation
dorsal (posterior) spinocerebellar tract	from muscle spindle (primarily) and golgi tendon organs	Ipsilateral Caudal Aspect of the body and legs
ventral (anterior) spinocerebellar tract	from golgi tendon organs	Ipsilateral Caudal Aspect of the body and legs
cuneocerebellar tract	from muscle spindle (primarily) and golgi tendon organs	Ipsilateral arm
rostral spinocerebellar tract	from golgi tendon organs	Ipsilateral arm

Pathway for dorsal and spinocuneocerebellar tracts

The sensory neurons synapse in an area known as Clarke's nucleus or "Clarke's column".

This is a column of relay neuron cell bodies within the medial gray matter within the spinal cord in layer VII (just beneath the dorsal horn), specifically between T1-L3. These neurons then send axons up the spinal cord, and project ipsilaterally to medial zones of the cerebellum through the inferior cerebellar peduncle.

Below L3, relevant neurons pass into the fasciculus gracilis (usually associated with the dorsal column-medial lemniscal system) until L3 where they synapse with Clarke's nucleus (leading to considerable caudal enlargement).

The neurons in the accessory cuneate nucleus have axons leading to the ipsilateral cerebellum via the inferior cerebellar peduncle.

Pathway for ventral and rostral spinocerebellar tracts

Some neurons of the ventral spinocerebellar tract instead form synapses with neurons in layer VII of L4-S3. Most of these fibers cross over to the contralateral lateral funiculus via the anterior white commissure and through the superior cerebellar peduncle. The fibers then often cross over again within the cerebellum to end on the ipsilateral side. For this reason the tract is sometimes termed the "double-crosser."

The Rostral Tract synapses at the dorsal horn lamina (intermediate gray zone) of the spinal cord and ascends ipsilaterally to the cerebellum through the inferior cerebellar peduncle.

References

^ Siegel, Allan, and Hreday N. Sapru. Essential Neuroscience. 2nd. Lippincott, 2011. 146-149.

External links

http://www.anatomyatlases.org/MicroscopicAnatomy/Section17/Plate17327.shtml

UpToDate Contents

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1. 脊髄小脳変性症 the spinocerebellar ataxias
2. 遺伝性運動失調の概要 overview of the hereditary ataxias
3. 急性小脳性運動失調 acute cerebellar ataxia
4. ハンチントン病：臨床的特徴および診断 huntington disease clinical features and diagnosis
5. Hemiplegic migraine

English Journal

Computational prediction of the PolyQ and CAG repeat spinocerebellar ataxia network based on sequence identity to untranslated regions.

Spence JL, Wallihan S.SourceOmnitron Biosciences, USA. Electronic address: jlspence@san.rr.com.
Gene.Gene.2012 Nov 10;509(2):273-81. doi: 10.1016/j.gene.2012.07.068. Epub 2012 Aug 6.
Computational prediction of biological networks would be a tremendous asset to systems biology and personalized medicine. In this paper, we use a moving window bioinformatic screen to identify transcripts with partial identity to the 5' and 3'UTRs of the polyQ spinocerebellar ataxia (SCA) genes ATXN
PMID 22967711

ATXN2 with intermediate-length CAG/CAA repeats does not seem to be a risk factor in hereditary spastic paraplegia.

Nielsen TT, Svenstrup K, Budtz-Jørgensen E, Eiberg H, Hasholt L, Nielsen JE.SourceDanish Dementia Research Centre, Neurogenetics Clinic, Department of Neurology, Rigshospitalet, Copenhagen University Hospital, Denmark; Department of Cellular and Molecular Medicine, Section of Neurogenetics, The Panum Institute, University of Copenhagen, Denmark.
Journal of the neurological sciences.J Neurol Sci.2012 Oct 15;321(1-2):100-2. Epub 2012 Aug 3.
Hereditary spastic paraplegia (HSP) confines a group of heterogeneous neurodegenerative disorders characterized by progressive spasticity and lower limb weakness. Age of onset is highly variable even in familial cases with known mutations suggesting that the disease is modulated by other yet unknown
PMID 22868089

Japanese Journal

Spinocerebellar ataxia type 31 (SCA31)の臨床像,画像所見 : Spinocerebellar ataxia type 6 (SCA6)との小脳外症候の比較検討

榊原聡子,饗場郁子,齋藤由扶子 [他]
臨床神経学 = Clinical neurology 54(6), 473-479, 2014-06
NAID 40020121503

脊髄小脳変性症の画像診断におけるvoxel-based morphometryの有用性

田中伸幸,南里和紀,田口丈士 [他]
Brain and nerve : 神経研究の進歩 66(6), 699-704, 2014-06
NAID 40020120041

脊髄小脳変性症 (特集神経難病とリハビリテーション)

尾花正義
総合リハビリテーション 42(6), 515-524, 2014-06
NAID 40020079285

Related Pictures

★リンクテーブル★

リンク元	「脊髄小脳」
拡張検索	「spinocerebellar ataxia type 4」「spinocerebellar ataxia」「anterior spinocerebellar tract neuron」「ventral spinocerebellar tract neuron」

「脊髄小脳」

Spinocerebellar tract
	Spinocerebellar tracts are labeled in blue at right.
Details
Latin	Tractus spinocerebellaris
Identifiers
Gray's	p.761
NeuroNames	ancil-2137625602
	Anatomical terms of neuroanatomy