Hello Ram Mohan Nayak

As i know about nerve fibres the diameters and numbers of fibres have been measured throughout the peripheral nervous system. The nerves of the muscles that act upon the outside world contain few fibres, having very large and medium-sized fibres but no very small ones. Thus the muscles of the head receive 6000 fibres, the largest of 30 μm diameter.

Diameters of different peripheral nerve fibres
Group A fibres
a) Afferent fibres -
Group I - 20 mm
Group II - 15 mm
Group III - 7mm
b) Efferent fibres -
alpha fibres - 17mm
beta fibres - 12mm
gamma fibres - 8mm
Group B fibres
Preganglionic Autonomic - 3mm
Group C fibres
Postganglionic Autonomic - 1.5mm