Dorsal Column Medial Lemniscal Pathway

Dorsal Column Medial Lemniscal Pathway

Write a short note on the dorsal column–medial lemniscal pathway.

Answer. The dorsal column–medial lemniscal pathway carries proprioceptive sensations (e.g. muscle and joint sense, fine touch, vibration sensations) from the opposite side of the body.

• First-order neurons are located in the dorsal root ganglia. Their axons enter the spinal cord through the medial root of the spinal nerves, ascend in the ipsilateral dorsal white column as fasciculus gracilis and fasciculus cuneatus, and terminate in gracile and cuneate nuclei, respectively, located in the caudal part of the medulla.
• Second-order neurons are located in the gracile and cuneate nuclei of the medulla. Their axons (internal arcuate fibers) decussate with those of opposite sides in the midline. After decussation, they form a compact fiber bundle (medial lemniscus), which ascends in the contralateral half of the brainstem and terminates in the ventral posterolateral (VPL) nucleus of the thalamus.
• Third-order neurons are located in the VPL nucleus of the thalamus. Their axons project to the primary somatosensory cortex.

Dorsal Column Medial Lemniscal Pathway Applied Anatomy

The damage of the dorsal column–-medial lemniscal pathway above the sensory decussation causes contralateral loss of proprioceptive sensations, while below the sensory decussation, it causes ipsilateral loss of proprioceptive sensations.