Which laminae do A-delta primary afferent fibers terminate in within Rexed's dorsal horn?

Which laminae do A-delta primary afferent fibers terminate in within Rexed's dorsal horn?

• A. Lamina I and Lamina V
• B. Lamina I
• C. Lamina II
• D. Lamina III

Answer: (A)

A-delta fibers are fast, sharp-pain afferents that synapse in the dorsal horn where immediate nociceptive signaling begins. They terminate primarily in the most superficial layer, lamina I, which contains nociceptive-specific neurons, and in lamina V, which houses wide-dynamic-range neurons that receive nociceptive input and integrate it with other sensory modalities. Lamina II, the substantia gelatinosa, is more dominated by C-fiber input and interneuron modulation, while lamina III is associated largely with mechanoreceptive (A-beta) input. Because A-delta fibers reliably convey fast pain signals and project to these two laminae, the correct termination pattern is lamina I and lamina V.

A-delta fibers are fast, sharp-pain afferents that synapse in the dorsal horn where immediate nociceptive signaling begins. They terminate primarily in the most superficial layer, lamina I, which contains nociceptive-specific neurons, and in lamina V, which houses wide-dynamic-range neurons that receive nociceptive input and integrate it with other sensory modalities. Lamina II, the substantia gelatinosa, is more dominated by C-fiber input and interneuron modulation, while lamina III is associated largely with mechanoreceptive (A-beta) input. Because A-delta fibers reliably convey fast pain signals and project to these two laminae, the correct termination pattern is lamina I and lamina V.