Final answer:
Lissauer's tract is a part of the spinothalamic pathway in the spinal cord that carries pain and temperature sensations from the peripheral nervous system to the brain.
Step-by-step explanation:
The relevance of Lissauer's tract to the somatosensory pathways is that it is a part of the spinothalamic pathway in the spinal cord. Lissauer's tract is responsible for carrying pain and temperature sensations from the peripheral nervous system to the brain. It is a lateral pathway that ascends ipsilaterally in the spinal cord.