Question

what nerve fibre types would be only found in a muscular branch of a peripheral nerve? GSA?

Answer 1

Nerve fiber type A is found in muscular branch of a peripheral nerve.

General Classification of Nerve Fibers;

The fibers are divided into types A, B and C, and the type A fibers are further subdivided into alpha, beta, gamma and delta fibers.

Type A fibers are the typical large myelinated fibers of spinal nerves. Type C fibers are the small unmyelinated nerve fibers that conduct impulses at low velocities. The C fibers constitute more than one half the sensory fibers in mostperipheral nerves as well as all the postganglionic autonomic fibers.

.A few large myelinated fibers can transmit impulses at velocities as great as 120m/sec, a distance in 1 second that is longer than a football field. Conversely, the smallest fibers transmit impulses as slowly as 0.5 m/sec requiring about 2 seconds to go from the big toe to the spinal cord.

Alternative Classification Used by Sensory Physiologists. Certain recording techniques have made it possible to separate the type A fibers into two subgroups , yet these same recording techniques cannot distinguish easilybetween A beta and A gamma fibers: Therefore, the following classification is frequently used by sensory physiologists.

Group A alpha from the annulospiral endings of muscle branch of a peripheral nerve (17 microns in diameter, these are a type A fibers in the generalclassification).

Group A beta,fibers from the Golgi tendon organs (average about 16 micrometers indiameter, these also are a-type A fibers).

Group B fibers from most discrete cutaneous tactile receptors and from theflower-spray endings of the muscle spindles (average about8 micrometers indiameter, these are 3- and y-type A fibers in the general classification).

Group C fibers  carrying temperature crude touch, and pricking painsensations (average about 3 micrometers in diameter, they are type A fibers inthe general classification).