The posterior trigeminothalamic tract (or dorsal trigeminothalamic tract) serves as a pain and temperature pathway from the face, head and neck (the facial equivalent of the spinothalamic tract). After entering the pons the central projections of the first order neurons descend to the medulla, forming the spinal trigeminal tract and synapse in the spinal trigeminal nucleus. Axons of the second order neurons cross the midline and terminate in the ventral posteromedial nucleus of the thalamus (as opposed to the ventral posterolateral nucleus as in the dorsal column-medial lemniscus pathway) to mediate conscious sensation of pain and temperature from the face, head and neck. The third order neuron in the thalamus then connects to the sensory cortex of the postcentral gyrus. The affective/motivational information is mediated by connections to reticular formation, midbrain, and the midline nuclei of the thalamus. The midline nuclei third order neurons then synapse to the cingulate and insular cortex.
Trigeminothalamic tracts (Netter image)