Which statement best describes the fast-sharp pain pathway?

Which statement best describes the fast-sharp pain pathway?

• A. A-delta fibers terminate in Lamina I and Lamina V and cross to contralateral lateral spinothalamic tract
• B. A-delta fibers terminate in Lamina II and III
• C. C fibers terminate in Lamina II
• D. A-delta fibers terminate in Lamina IV only

Answer: (A)

Fast sharp pain is carried by myelinated A-delta fibers. These afferents terminate in the dorsal horn primarily in Lamina I and Lamina V, where the second-order neurons begin, then cross the midline via the anterior white commissure and ascend in the contralateral lateral spinothalamic tract to the thalamus and somatosensory cortex. This wiring produces the rapid, well-localized pain that you can point to. In contrast, C fibers (unmyelinated) convey slow dull pain and mainly terminate in Lamina II, which is part of a different, slower pathway. So the description of A-delta fibers terminating in Lamina I and Lamina V and crossing to the contralateral lateral spinothalamic tract best describes the fast-sharp pain pathway.

Fast sharp pain is carried by myelinated A-delta fibers. These afferents terminate in the dorsal horn primarily in Lamina I and Lamina V, where the second-order neurons begin, then cross the midline via the anterior white commissure and ascend in the contralateral lateral spinothalamic tract to the thalamus and somatosensory cortex. This wiring produces the rapid, well-localized pain that you can point to. In contrast, C fibers (unmyelinated) convey slow dull pain and mainly terminate in Lamina II, which is part of a different, slower pathway. So the description of A-delta fibers terminating in Lamina I and Lamina V and crossing to the contralateral lateral spinothalamic tract best describes the fast-sharp pain pathway.