Anatomy, physiology and pharmacology of pain

Pain is a complex emotional experience arising from integrated processing of nociceptive input subject to inhibitory and excitatory modulatory influences at multiple levels of the neuraxis. Transmembrane protein ion channels transduce mechanical, thermal and chemical tissue injury into electrophysiological signals that are transmitted to supraspinal structures via multiple synapses that exhibit neuroplasticity dependent upon coincident neuronal and glial activation. There are therefore multiple potential pharmacological targets and the complexity of pain perception necessitates multimodal management.