ABSTRACT
Pain is 'an unpleasant sensory and emotional experience associated with actual or potential tissue damage'. Pain can be classified according to its chronicity as acute and chronic. It can be classified according to its nature as nociceptive and neuropathic. Nociceptors respond to noxious stimuli, which may be thermal, mechanical or chemical and neuropathic is due to dysfunction of the nervous system. The chapter provides schematic representation of pain pathways and characteristics of different nerve fibres. Pain receptors are unmyelinated nerve endings that are abundant in skin and musculoskeletal tissue, and that respond to thermal, mechanical and chemical stimuli. They are classified according to their sensitivity to the type of stimulus as unimodal, which responds to pinprick and sudden heat; and polymodal, which responds to pressure, heat, cold, chemicals and tissue damage.
