Fibres most sensitive to local anesthesia are

Group C nerve fibers are one of three classes of nerve fiber in the central nervous system (CNS) and peripheral nervous system (PNS). The C group fibers are unmyelinated and have a small diameter and low conduction velocity, whereas Groups A and B are myelinated. Group C fibers include postganglionic fibers in the autonomic nervous system (ANS), and nerve fibers at the dorsal roots (IV fiber). These fibers carry sensory information C fibers and A-d are sensitive to local anesthesia Ref guyton and hall textbook of medical physiology Edition 12 pg 701 Group C nerve fiber C fiber not labeled, but substantia gelatinosa of Rolando is Rexed lamina II, labeled at upper left.