Final answer:
The spinothalamic tract is responsible for carrying signals of crude touch, pain, and temperature to the brain stem and thalamus. It is one of the two major ascending sensory pathways in the spinal cord, with the dorsal column system being the other, responsible for fine touch sensations.
Step-by-step explanation:
The white matter tract that carries signals of crude touch, pain, and temperature to the brain stem and thalamus is the spinothalamic tract. This pathway begins with neurons in the dorsal root ganglion, which transmit axons to the dorsal horn of the spinal cord. There, they synapse with the second neuron in the pathway. The axons from these second neurons decussate, or cross over, within the spinal cord at the level of entry and then ascend contralaterally (on the opposite side) to the brain before entering the thalamus. Subsequent neurons then project to the somatosensory cortex in the cerebral cortex. This process is crucial for the ability to feel pain and temperature, and it is distinct from the dorsal column system, which is primarily responsible for fine touch sensations and proprioception. Testing these two pathways can reveal whether they are properly functioning and can help diagnose neural damage.