Large, medium and small neurons form the DRG population. These pseudo-unipolar neurons have a peripheral and a central projection arising from one short soma projection.

• Large, medium and small neurons form the DRG population. These pseudo-unipolar neurons have a peripheral and a central projection arising from one short soma projection.

• The peripheral endings terminate as sensors generating receptor potentials in receptor organs of supporting cells and the DRG teledendron. No receptor cells are involved.

• The central projections enter either the medial or else the lateral division (pain) of cord roots. Three morphological categories of neuron sizes fit with their function as: large (1A) axons that are monosynaptic on motor neurons; medium polysynaptic neurons form some reflexes and other ascend as axons in the dorsal column and end in the brainstem.

• Small neurons, for pain and touch, enter the dorsal lateral fasciculus of Lissauer where axons ascend/ descend over three segments forming the pain and light touch pathways.