In the dorsal column pathway, which nuclei participate in decussation?

In the dorsal column pathway, which nuclei participate in decussation?

• A. Gracile and cuneate nuclei.
• B. Substantia nigra.
• C. Cochlear nuclei.
• D. Dorsal horn.

Answer: (A)

Decussation in the dorsal column pathway occurs when the second-order neurons in the gracile and cuneate nuclei send their axons across the midline as internal arcuate fibers, forming the medial lemniscus that ascends to the thalamus. The gracile nucleus handles lower-body input and the cuneate nucleus handles upper-body input, so these two nuclei are the ones that participate in crossing over. The other structures don’t participate in this decussation: the substantia nigra is a midbrain motor-related structure, the cochlear nuclei process auditory information, and the dorsal horn is where initial sensory fibers synapse in the spinal cord.

Decussation in the dorsal column pathway occurs when the second-order neurons in the gracile and cuneate nuclei send their axons across the midline as internal arcuate fibers, forming the medial lemniscus that ascends to the thalamus. The gracile nucleus handles lower-body input and the cuneate nucleus handles upper-body input, so these two nuclei are the ones that participate in crossing over. The other structures don’t participate in this decussation: the substantia nigra is a midbrain motor-related structure, the cochlear nuclei process auditory information, and the dorsal horn is where initial sensory fibers synapse in the spinal cord.