In this chapter, the mechanism of pain, pain pathway from Oro-facial area
and the physiological principle of pain have been discussed in detail. In order to
understand the mode of action of local anesthesia, it is essential to understand the pain
physiology. This chapter contains the essential details of pain physiology that may be
needed for an understanding of the mechanism of local anesthesia. The endogenous
analgesic system is an important modulator part for pain intensity and a major
contributor to pain gate theory, all that has been discussed in a concise and precise way
to give the complex information in a simple way to understand and remember.
Keywords: Endogenous pain killer system, Impulse generation, Pain fibers, Pain
pathway, Pain physiology, Principle of pharmacology for pain management.
