Dorsal columns in the context of "Dorsal column-medial lemniscus pathway"

The dorsal column–medial lemniscus pathway (DCML) (also known as the posterior column-medial lemniscus pathway (PCML) is the major sensory pathway of the central nervous system that conveys sensations of fine touch, vibration, two-point discrimination, and proprioception (body position) from the skin and joints. It transmits this information to the somatosensory cortex of the postcentral gyrus in the parietal lobe of the brain. The pathway receives information from sensory receptors throughout the body, and carries this in the gracile fasciculus and the cuneate fasciculus, tracts that make up the white matter dorsal columns (also known as the posterior funiculi) of the spinal cord. At the level of the medulla oblongata, the fibers of the tracts decussate and are continued in the medial lemniscus, on to the thalamus and relayed from there through the internal capsule and transmitted to the somatosensory cortex. The name dorsal-column medial lemniscus comes from the two structures that carry the sensory information: the dorsal columns of the spinal cord, and the medial lemniscus in the brainstem.

There are three groupings of neurons that are involved in the pathway: first-order neurons, second-order neurons, and third-order neurons. The first-order neurons are sensory neurons located in the dorsal root ganglia, that send their afferent fibers through the two dorsal columns. The first-order axons make contact with second-order neurons of the dorsal column nuclei (the gracile nucleus and the cuneate nucleus) in the lower medulla. The second-order neurons send their axons to the thalamus. The third-order neurons are in the ventral posterolateral nucleus in the thalamus and fibres from these ascend to the postcentral gyrus.