The pathway from the spinal cord to the cerebellum takes different courses, depending on whether the upper or lower limbs are being considered.

The Dorsal Spino-cerebellar Tract

The afferent pathways from the lower half of the body concerned with kinaesthesia enter the dorsal columns and ascend to Clarke's nucleus, where the afferents synapse on second order neurones. These project rostrally on the same side of the cord to reach the cerebellum.

The ventral spinocerebellar tract conveys runs in parallel with the dorsal tract in a functional sense, in that each consist of two neurones in series, and both have an inspilateral relationship between the cord and the cerebellum.

However the ventral tract takes a more circuitous route, crossing to the opposite side of the cord in the anterior commissure, then crossing again in the brainstem - thus performing a double crossover.

Clarke's nucleus extends from C8 - L2/L3 and is sometimes called Clarke's Column, or the Nucleus Dorsalis. Afferents from the upper limb therefore enter the cord above the rostral end of the column.

As Clarke's nucleus does not extend above C8, the dorsal spinocerebellar tract does not convey information from the upper limb.

Afferents from the Upper Limb travel rostrally in the dorsal columns and synapse in the accessory cuneate nuclei, which project to the same side of the cerebellum. This pathway for proprioceptive information from upper limbs is sometimes called the cuneocerebellar tract.

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Romberg's Test is a clinical test used to examine the integrity if the spinal input to the cerebellum. Normal balance depends on visual, vestibular and spinal inputs to the cerebellum, and if the spinal pathway is disturbed the patient becomes ataxic.

When a patient is asked to stand with his feet together, then close his eyes, he will sway and possibly even fall over if the spinal pathway is deficient, because of the lack of visual input. This would be the case of a positive Romberg's Test.

Spino-Cerebellar Ataxia is a rare inherited degenerative disease of the nervous system that is characterised by ataxia - a term that describes a group of neurological disorders that affect co-ordination, balance and speech. The spino-cerebellar tracts are a part of the CNS that shows signs of degeneration in this condition.