Fiber Analysis of the Lumbar Spinal Roots and Their Sciatic Branches in Rats

Abstract

The nerve fiber analysis of the rat dorsal and ventral spinal roots extending to the sciatic nerve and of the sciatic branches such as the lateral and medial gastrocnemius nerves and the cutaneous nerve innervating the lateral aspect of thigh was done. Fiber counting was also made by microdissection method. To know the distribution of afferent and efferent components in a nerve, deefferentation was made by sectioning the relevant ventral roots. Main results obtained were as follows: 1) The sciatic nerve receives its constituent fibers mainly from L5 and partly from L4 and L6. 2) In the dorsal roots examined, the fibers larger than 12 μ occupy a rather small portion of the total composition, and the afferent component of the hind-limb muscle nerves practically lacks fibers larger than 12 μ. 3) The cutaneous nerve is devoid of efferent fibers and larger fibers characteristic of muscle nerves. 4) The total number of a peripheral nerve composition corresponds quite well on both sides of an animal and among different animals. © 1970, Tohoku University Medical Press. All rights reserved.