The nervous system is a communication network that allows an organism to interact in appropriate ways with its environment. If the gap between the cut ends and the nerve is more than 3mm regeneration is difficult. Regeneration in such cases may be helped by surgical closure. The sprout emerging out of the proximal stumps in some cases may expand and develop a neuroma. In such cases regeneration does not occur. Nerve injury may also result to certain diseases for example: Leprosy (infestation of Schwann cell by lepra bacillus), diabetic neuropathy (a non-infective degeneration of peripheral nerves in untreated diabetes). In cases where neurolemma is absent and there can be no regeneration. Nerve fibers of CNS once degenerated never regenerate as the nerves have no neurolemma for example: nerves of CNS, optic nerve. The purpose of this book was an attempt to cover the nerve physiology and to discuss the anatomy of trigeminal nerve.