Nerve fibers involved in proprioception
Ans. (a) Type A fiber(Ref: Ganong, 25th ed/p.94)Erlanger and Gasser classified nerve fibers in to three types A, B and C based on their diameter, degree of myelination and conduction velocities.The classification is for both sensory and motor nerve fibers. The classification is as follows,Fiber TypeMyelin Present or AbsentDiameter(um)Conduction Velocity (m/s)FunctionsA aMyelinated12-20 (Largest)70-120 (Highest)Proprioception; somatic motorA bMyelinated5-1230-70Touch, pressureA gMyelinated3-615-30Motor to muscle spindlesA dMyelinated2-512-30Pain, temperatureBMyelinated<33-15Preganglionic autonomicC, dorsal rootUnmyelinated0.4-1.2 (Smallest)0.5-2 (lowest)Pain, temperatureC, SympatheticUnmyelinated0.3-1.30.7-2.3Postganglionic sympathetic
Type A fiber
Type B fiber
Type C fiber
Type IV fiber
Nervous System