Compare DC-ML and Anterolateral based on size:

• A. DCML: Larger, myelinated fibers; Anterolateral: Smaller, myelinated fibers
• B. DCML: Smaller, unmyelinated; Anterolateral: Larger, myelinated
• C. DCML: Larger, unmyelinated; Anterolateral: Smaller, unmyelinated
• D. DCML: Similar in size

Answer: (A)

Fiber diameter and how heavily the fibers are myelinated shape how fast a pathway transmits signals and what it mainly carries. The dorsal column–medial lemniscus system uses large-diameter, heavily myelinated fibers (the Aβ fibers) that rapidly convey precise touch, vibration, and proprioception. The anterolateral (spinothalamic) pathway relies on smaller-diameter fibers that are less myelinated (including Aδ for fast pain and temperature, and C fibers which are unmyelinated for slow pain). Because the dorsal-column fibers are larger and more heavily myelinated, they conduct faster and carry different sensations than the smaller, less-myelinated fibers of the anterolateral pathway. That’s why the statement that DCML fibers are larger and myelinated while the anterolateral fibers are smaller best captures the difference.