TABLE 21-2. - Peripheral Nerve Fiber Categories and Functions

Fiber category Size (microns) Speed (meters/second) Function

Aα;
Group IA and IB afferents

15

60-100

Large motor axons; Muscle stretch and tension sensory axons

Aβ;
Group II afferents

12-14

30-60

Touch, pressure, vibration and joint position sensory axons

8-10

15-30

Gamma efferent motor axons

Aδ;
Group III afferents

6-8

10-15

Sharp pain, very light touch & temperature sensation

B

2-5

3-10

Sympathetic preganglionic motor axons

C;
Group IV afferents

<1

<1.5

Dull, aching, burning pain and temperature sensation

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