Gracile fasciculus

The gracile fasciculus is the tract or bundle that consists of first-order neurons of the dorsal column-medial lemniscal pathway, responsible for transmitting sensations of vibration, conscious proprioception, and two-point discrimination from the lower extremities. This fasciculus extends throughout the entire length of the spinal cord, ascending in the dorsal columns to terminate by synapsing with the gracile nuclei located in the gracile tubercle of the medulla.

Don’t confuse the gracile fasciculus with the cuneate fasciculus: The cuneate fasciculus, also part of the dorsal column pathway, similarly conveys sensations of vibration, conscious proprioception, and two-point discrimination but differs in its origin, as it transmits sensory inputs from the upper extremities (excluding the head). Unlike the gracile fasciculus, the cuneate fasciculus appears only at spinal segment level T6 and above and is absent in the lower spinal cord. It remains lateral to the gracile fasciculus along its course and terminates by synapsing in the cuneate nuclei within the cuneate tubercle.

The two fasciculi—the gracile and cuneate—are anatomically divided by an intervening posterior intermediate sulcus.