Gracile fasciculus

Last revised by Edward Henley on 21 Mar 2022

The gracile fasciculus, also known as the fasciculus gracilis (plural: fasciculi graciles) or column of Goll, represents the medial portion of the dorsal columns and carries input from below and including T7 1.

The gracile fasciculus is responsible for transmitting vibration, conscious proprioception, and fine (discriminative) touch sensations from the lower body 1.

First-order neurons from peripheral receptors enter the spinal cord via the posterior roots, and unlike first-order neurons from the spinothalamic tract, do not synapse in the posterior grey horn of the cord 1. Thus, these first-order neurons form the gracile fasciculus of the dorsal columns if input was from T7 or below 1. If input is from between and including C1 and T6, the cuneate fasciculus is formed instead, which is discussed separately. 

Unlike fibers of the spinothalamic tract, these first-order neurons in the gracile fasciculus continue to ascend without decussation 1. This ipsilateral ascension continues until the medulla oblongata of the brainstem 1. Fibers of this tract are somatotopically organized for their entire course 1.

Upon reaching the gracile nucleus of the caudal medulla oblongata these first-order neurons terminate and synapse with second-order neurons 1. These second-order neurons then decussate to the contralateral side, known as the internal arcuate fibers during this decussation 1. These decussated neurons continue to ascend as part of the medial lemniscus where they terminate in the ventral posterior nucleus of the thalamus 1. Here, they synapse with third-order neurons 1. It is these third-order neurons that finally project to the primary somatosensory area on the ipsilateral side of the cerebral cortex 1.

Named after Friedrich Goll (1829-1903), a Swiss anatomist 2.

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