The fibre which is the thickest in human nerve is
Proprioception is carried by the thickest fibre A alpha (12-20 micrometer). Touch by A beta (5-12 um)Pain, temperature by A delta (2-5 um). Ref: Ganong&;s Review of medical physiology;25th edition; pg: 94; table 4-1.
Touch
Pain
Temperature
Proprioception
Nervous system