Which tract contains axons from the upper body and arms?

• A. Fasciculus cuneatus
• B. Fasciculus gracilis
• C. Spinothalamic tract
• D. Lateral corticospinal tract

Answer: (A)

In the dorsal column–medial lemniscus system, fine touch, vibration, and proprioception from the body travel upward in two parallel tracts. Axons from the upper body and arms are carried by the fasciculus cuneatus, which lies laterally in the dorsal columns of the cervical and upper thoracic cord. In contrast, axons from the lower body and legs travel in the fasciculus gracilis, which is located medially. So, the tract that contains axons from the upper body and arms is the fasciculus cuneatus.

For context, these dorsal column fibers ascend ipsilaterally to the medulla, synapse in the nucleus cuneatus (upper body) or nucleus gracilis (lower body), cross as internal arcuate fibers, and then form the medial lemniscus to reach the thalamus. The other options don’t fit this sensory pathway: the spinothalamic tract carries pain and temperature, and the lateral corticospinal tract is a motor pathway.