Neurons leaving lamina V cross immediately to contralateral lateral spinothalamic tract and ascend. Which lamina is associated with these crossing neurons?

Neurons leaving lamina V cross immediately to contralateral lateral spinothalamic tract and ascend. Which lamina is associated with these crossing neurons?

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

Answer: (A)

Pain and temperature information is carried by second-order neurons that cross to the opposite side soon after they enter the spinal cord. The crossing happens at the ventral (anterior) white commissure, and these neurons then ascend in the contralateral lateral spinothalamic tract to reach the thalamus and cortex. The cells that do this crossing and contribute to the contralateral spinothalamic tract are located in lamina V of the dorsal horn. These wide-dynamic-range neurons receive nociceptive input and send axons that cross immediately and join the contralateral tract, forming the fast pain pathway. While other laminae, like lamina I, also participate in nociceptive transmission, the description of immediate crossing specifically points to lamina V as the source of those crossing neurons. After crossing, the pathway continues upward in the lateral funiculus to reach higher centers.

Pain and temperature information is carried by second-order neurons that cross to the opposite side soon after they enter the spinal cord. The crossing happens at the ventral (anterior) white commissure, and these neurons then ascend in the contralateral lateral spinothalamic tract to reach the thalamus and cortex. The cells that do this crossing and contribute to the contralateral spinothalamic tract are located in lamina V of the dorsal horn. These wide-dynamic-range neurons receive nociceptive input and send axons that cross immediately and join the contralateral tract, forming the fast pain pathway. While other laminae, like lamina I, also participate in nociceptive transmission, the description of immediate crossing specifically points to lamina V as the source of those crossing neurons. After crossing, the pathway continues upward in the lateral funiculus to reach higher centers.