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Nerve Conduction

Aβ sensory fiber

Myelinated touch and secondary spindle afferents. Three tables print 35–75 metres per second; nearby chapters print a slightly different band.

Also known as Group II, A-beta afferent
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Conduction velocity

35–75m/s

Sensory afferent class. Textbook range 35–75 m/s. The rank uses the top of the range. The row shows the whole range.

OfficialFundamental Neuroscience for Basic and Clinical Applications (opens source in a new tab)

Mechanism

Why it's so fast

Aβ fibers stay fast by keeping their myelin, and they slow relative to Aα fibers because the axon is narrower.

  1. Still saltatory

    Myelin remains, so the impulse still jumps node to node. The diameter in the shared table is 6–12 µm, about half the Aα class or less, and the conduction band drops with it.

  2. Touch, not a reflex timer

    These afferents supply skin mechanoreceptors and secondary muscle spindles. The figure is how fast the axon conducts, not how fast a person reacts.

  3. Why 35–75 stays

    Henley, River Publishers, and Haines print 35–75 m/s. Guyton's 30–70 and an NCBI chapter's 33–75 are real disagreements. They are disclosed, not averaged in.

Faster than an Aδ fiber, and slower than an Aα sensory fiber.

Provenance

Every measurement

Claimed, measured and official figures side by side, each with its source. The ranked figure is marked.

  1. 35–75m/sRanked figure

    Sensory afferent class. Textbook range 35–75 m/s. The rank uses the top of the range. The row shows the whole range.

    Guyton and Hall print Aβ tactile fibers at 30–70 m/s. NCBI Bookshelf NBK7514 prints Aβ at 33–75 m/s, with a diameter there of 6–22 µm. The ranked range stays 35–75 m/s because that is the band the three tables print. The row is not an average.

    Official
    Fundamental Neuroscience for Basic and Clinical Applications (opens source in a new tab)

Reference

Specs

Class
Aβ, Group II
Diameter
6–12 µm
Myelin
Yes
Range
35–75 m/s

Context

Background

Aβ fibers are still myelinated, and thinner than Aα. They carry touch, skin mechanoreception, and the secondary endings of muscle spindles. Saltatory conduction remains, with a slower band because the axon is narrower.

The three tables print 35–75 m/s and a diameter of 6–12 µm. Guyton and Hall's tactile band is 30–70 m/s, and an NCBI Bookshelf chapter prints 33–75 m/s. Those disagreements are in the note. They do not replace the shared range, and the rank uses 75 m/s, the top of 35–75.

Spot a wrong number?

Every report is read by a person, and corrections are dated on the page.