Somatosensory System Quiz

See Dorsal Column Medial Lemniscus Pathway. Option D is correct. The dorsal column medial lemniscus (DCML) pathway is the route that carries vibration, proprioception (the sense of where your joints and limbs are in space), fine touch and two-point discrimination (the ability to tell two close points of contact apart) to the brain. The name tells you the route: the dorsal columns are the tracts at the back of the spinal cord, and the medial lemniscus is the ribbon of fibres that continues up through the brainstem. Fibres rise on the same side as the body part they serve until they reach the medulla (the lowest part of the brainstem), where they synapse in the gracile and cuneate nuclei, cross the midline, and travel up to the thalamus and then the sensory cortex. Because the crossing happens high up, a lesion within the spinal cord causes loss on the same side as the lesion. Memory aid: the dorsal columns carry the fine, precise senses, the ones you use to feel a tuning fork or find your keys by touch in a pocket.

• Pathway: the dorsal column medial lemniscus pathway carries vibration, proprioception, fine touch and two-point discrimination.
• Route: fibres rise on the same side to the gracile and cuneate nuclei in the medulla, then cross to the thalamus and sensory cortex.
• Cord lesion: because the crossing is high up, loss is on the same side as the lesion.