Posterior funiculus

The posterior funiculus (a.k.a. posterior column or dorsal column) refers to the sensory white matter tracts which reside between the posterior median fissure in the midline and the point of entry of the posterior nerve rootlets into the spinal cord, posterolaterally.

The posterior funiculus comprises of ascending white matter tracts which belong to the dorsal column medial leminiscal pathway. The ascending neurons in the dorsal column transmit sensory information of vibration, proprioception and 2-point discrimination from the peripheral body up to the higher neural centers in the brain.

This posterior funiculus (or dorsal column) can be sub-divided into gracile fasciculus and cuneate fasciculus. Both fasciculi represent the first order neurons of the dorsal column medial leminiscal sensory pathway, however, the gracile fasciculus lies medially and transmits the above-mentioned sensations from the lower body (T6 spinal segment level and below), while the cuneate fasciculus lies laterally and transmits same information from the upper body (T6 spinal segment above). The two fasciculi are separated from each other by an intermediolateral sulcus.

The sensory fibers in the posterior funiculus ascend uncrossed prior to synapsing in their respective nuclei in the caudal medulla, i.e. the nucleus gracilis and nucleus cuneatus. The posterior funiculus then crosses over to the opposite side as the ‘internal arcuate fibers’ and then ascends through the brainstem–as a much more ventrally placed structure–now called ‘medial leminiscus’. The sensory information is eventually relayed to the thalamus and the primary sensory cortex.