Spinocerebellar Pathways

A second type of sensory information enters the spinal cord through the dorsal columns. These fibers generally carry spinocerebellar impulses that terminate in various regions of the cerebellum and thus do not reach a level of conscious sensation.

The dorsal spino-olivary tract ascends within the dorsal columns, synapses in the cuneatus and gracilis nuclei, and then relays impulses to the contralateral accessory olivary nucleus. These fibers arise in the spinal cord and are activated by cutaneous and group Ib receptor afferents. The function of these fibers is largely spinocerebellar. There are fibers traveling in the anterior funiculi that have a similar termination and are referred to as the anterospino-olivary tract.

The dorsal spinocerebellar tract (DSCT) arises from neurons in the dorsal nucleus of Clarke from the T1 to L2 levels. The principal afferent fibers to Clarke's nucleus are collaterals of primary afferent fibers that are observed to descend directly from the dorsal columns. These cells have afferent peripheral inputs from muscle spindles, Golgi tendon organs, and touch and pressure receptors. The fibers enter the cerebellum through the inferior cerebellar peduncle in the medulla and terminate on the ipsilateral vermis. These impulses are utilized in the fine coordination of posture and movement of individual limb muscles.

The ventral spinocerebellar tract arises from cells in the dorsal horn and ascends largely contralaterally in the lateral funiculus of the cord ventral to the dorsal spinocerebellar tract. The fibers come from levels below the midthoracic cord. These fibers enter the cerebellum through the superior cerebellar peduncle.

The cuneocerebellar tract (CCT) is the forelimb equivalent of the DSCT. It consists of two separate components: one exteroceptive, which is activated by cutaneous afferents and higher threshold muscle afferents, and one proprioceptive, which is activated by group I muscle afferents. The CCT terminates ipsilaterally in lobule V of the anterior lobe of the cerebellum. y

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