What is the diameter range of C fibers?

What is the diameter range of C fibers?

• A. 1-4 um
• B. 2-3 um
• C. 0.1-0.3 um
• D. 0.4-1.2 um

Answer: (D)

C fibers are the smallest peripheral nerve fibers and are unmyelinated, which gives them very slow conduction. Their diameter is typically about 0.4 to 1.2 micrometers, so the range 0.4–1.2 μm best fits their size. The other ranges are larger or even smaller than the typical C-fiber diameter: larger ranges align with myelinated A fibers (which conduct faster), while the submicron range is too small for standard C fibers. Thus, the correct diameter range for C fibers is 0.4–1.2 micrometers.

C fibers are the smallest peripheral nerve fibers and are unmyelinated, which gives them very slow conduction. Their diameter is typically about 0.4 to 1.2 micrometers, so the range 0.4–1.2 μm best fits their size. The other ranges are larger or even smaller than the typical C-fiber diameter: larger ranges align with myelinated A fibers (which conduct faster), while the submicron range is too small for standard C fibers. Thus, the correct diameter range for C fibers is 0.4–1.2 micrometers.