A person wakes up with pain, paraesthesia, tingling in the arms. He had slept with arm below the head. Which fibers are involved?
In the general classification, the fibers are divided into types A and C, and the type A fibers are fuher subdivided into a, b, g, and d fibers. Alternative classification:Group Ia. Fibers from the annulospiral endings of muscle spindles (about 17 microns in diameter on average; these fibers are a-type A fibers in the general classification).Group Ib. Fibers from the Golgi tendon organs (about 16 micrometers in diameter on average; these fibers also are a-type A fibers).Group II. Fibers from most discrete cutaneous tactile receptors and from the flower-spray endings of the muscle spindles (about 8 micrometers in diameter on average; these fibers are b- and g-type A fibers in the general classification).Group III. Fibers carrying temperature, crude touch, and pricking pain sensations (about 3 micrometers in diameter on average; they are d-type A fibers in the general classification).Group IV. Unmyelinated fibers carrying pain, itch, temperature, and crude touch sensations (0.5 to 2 micrometers in diameter; they are type C fibers in the general classification).Ref: Guyton; 13th edition; Chapter 47; Sensory Receptors, Neuronal Circuits for Processing Information
Type A fibers
Type B
Type C (pain)
Type C (postganglionic)
General physiology