18 Spinocerebellar Tract

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    Spinocerebellar Tracts

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    Pathways to the Cerebellum

    n Posterior Spinocerebellar tract

    nAnterior Spinocerebellar tract

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    Posterior Spinocerebellar

    Tractn Function

    n Coordination of limb movementsn Maintenance of posture

    n Locationn Posterolateral part of the lateral white

    funiculus

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    Posterior Spinocerebellar

    Tract3.It lies at the surface of the spinal

    cord.

    4.Fibres in the tract project ipsilaterally,--To the vermis of the cerebellum through the

    inferior cerebellar peduncle.

    5.The posterior spinocerebellar tract is

    principally concerned with the ipsilateralleg.

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    Anterior Spinocerebellar

    Tractn Function.

    n Mainly concerned with movements of thelimbs as whole.

    n Receptors come from.n The trunk.n The upper limbs.n The lower limbs.

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    Anterior Spinocerebellar

    TractFirst order neurons.

    1.Cells in the body of the

    lumbosacral posterior horn,together with.

    -Cells on the lateral surface of the

    anterior horn (spinal border cells).---Give rise to the anteriorspinocerebellar tract.

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    Anterior Spinocerebellar

    Tract2.The inputs to these tract cells are more

    complex than those of the

    posterior spinocerebellar tract.They come.

    ---From group I muscle afferent (mainlyGolgi tendon organs),

    ---From a wide variety ofcutaneousreceptors including spinal interneuronsand from fibres of descending tracts.

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    Anterior Spinocerebellar

    TractSecond order neurons.

    1.Neurons are located in the nucleus

    dorsalis of clarke.2.The tract is crossed at the level of the

    spinal cord, in contrast to the posteriorspinocerebellar tract.

    3.These fibers are located on to theventrolateral aspect of lateral whitefuniculus.

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    Anterior Spinocerebellar

    Tract5.It enters the cerebellum via the

    superior cerebellar peduncle.

    6.Most of its fibres recross the midlinebefore ending in the vermis of the

    anterior lobe.

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    Anterior Spinocerebellar

    Tract7.Thus, the fibres of the anterior

    spinocerebellar tract ultimately end

    in the cerebellum on the ipsilateralside to their origin.

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    Cuneocerebellar Tract1.Most spinocerebellar-type afferents that

    enter in cervical and upper thoracicsegments do not project to nucleusdorsalis.

    2.They travel in the fasciculus cuneatus,

    ---To a nucleus in the medulla,

    ---Analogous to nucleus dorsalis,---Called the lateral (or external)

    cuneate nucleus.

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    Cuneocerebellar Tract3.It is located just lateral to the

    nucleus cuneatus.

    4.Axons of these cells form thecuneocerebellar tract.

    5.They also project ipsilaterally to

    the vermis of the cerebellumthrough the inferior cerebellarpeduncle.

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    Spino-olivary Tractn Function.

    n Conveys information to the cerebellumfrom cutaneous and proprioceptive organs.

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    Spino-olivary Tractn Third order neurons.

    n Located in the inferior olivary nucleus ofthe medulla oblongata.

    nAxons of the third order neurons cross themidline and enter the cerebellum theinferior cerebellar peduncle.

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