Dorsal column-medial lemniscus pathway > Open medulla
Gracile & Cuneate tracts (of the dorsal column)
- The gracile tract is a sensory tract in the dorsal column, serving the lower part of the body and lower limbs. In the cervical region it is joined laterally by the cuneate tract which serves structures above the upper thorax, including the upper limb.
- Both gracile and cuneate tracts contain axons of first-order sensory neurons, whose cell bodies are in the dorsal root ganglia and sensory terminals in the periphery.
- Their axons pass to the dorsal medulla where they synapse with axons in the gracile and cuneate nuclei. The axons of those neurons then cross over ventrally (arcuate axons) and form a ribbon-like tract called the medial lemniscus, which passes to the thalamus (nucleus VPL – lateral ventro-posterior nucleus) to synapse again. Thalamic neurons then send their axons through the internal capsule to the somatosensory cortex.
- Gracile and cuneate tracts carry information about discriminative touch, conscious proprioception and vibration sense.
