Final answer:
The axons of mechanoreceptors in the dorsal column-pathway remain ipsilateral as they ascend in the spinal cord until reaching the medulla, where they cross to the contralateral side. The spinothalamic pathway crosses almost immediately at the level of entry and ascends contralaterally, providing different diagnostic clues for spinal cord damage.
Step-by-step explanation:
The axons of mechanoreceptors primarily turn and ascend in the ipsilateral dorsal columns. The dorsal column pathway is responsible for conveying sensations such as fine touch, vibration, and proprioception from the site of stimulus to the brain. These axons enter the dorsal column of the spinal cord and remain on the same side, ascending ipsilaterally until they reach the medulla, where they decussate, or cross over, to the opposite side.
Conversely, the axons from the spinothalamic tract, which convey pain and temperature sensations, enter the spinal cord and decussate almost immediately, ascending in the contralateral lateral column to the side of entry. Hence, when assessing damage to the spinal cord, evaluating the function of these pathways can provide critical information. For example, a hemisection of the spinal cord can result in loss of fine touch and proprioceptive sensations ipsilaterally at the level of damage and below due to interruption of the dorsal column pathways, while pain and temperature sensations would be lost contralaterally because of the spinothalamic pathway's immediate decussation.