The dorsal column–medial lemniscus pathway transmits which modalities?

• A. Fine touch, vibration, proprioception, and two-point discrimination
• B. Pain and temperature
• C. Motor commands
• D. Olfactory information

Answer: (B)

The dorsal column–medial lemniscus pathway carries high-fidelity somatosensory information related to fine touch, vibration, proprioception, and two-point discrimination. These modalities require precise spatial resolution and quick, accurate localization on the body. The information travels ipsilaterally through the dorsal columns (gracile and cuneate fasciculi) to the medulla, where it synapses in the nucleus gracilis and nucleus cuneatus. The fibers then cross over (as internal arcuate fibers) and ascend as the medial lemniscus to the ventral posterior lateral nucleus of the thalamus, finally reaching the somatosensory cortex. In contrast, pain and temperature are carried by the spinothalamic tract; motor commands are conveyed by motor pathways like the corticospinal tract; and olfactory information uses separate olfactory pathways. Clinically, tests of vibration sense and two-point discrimination assess DCML integrity.