Pain Pathways

step 1 of Spinothalamic Pathway

DRG sensory neurons synapse on second order-neurons in ipsilateral dorsal horn

step 2 of Spinothalamic Pathway

Dorsal horn afferents cross midline in that segment, ascend, and synapse on third-order neurons in contralateral thalamus in VPL

step 3 of Spinothalamic Pathway

Thalamic afferents synapse on neurons in primary sensory cortex

step 1 of Dorsal Trigeminothalamic Pathway

First Order Neuron in trigeminal ganglia relays peripheral information into pons

step 2 of Dorsal Trigeminothalamic Pathway

Afferents synapse on second order neurons in ipsilateral medulla

step 3 of Dorsal Trigeminothalamic Pathway

Medullary afferents cross midline, ascend, and synapse on third-order neurons in contralateral thalamus in VPM

step 4 of Dorsal Trigeminothalamic Pathway

Thalamic afferents synapse on neurons in primary sensory cortex