Modified Sihler's technique for studying the distribution of intramuscular nerve branches in mammalian skeletal muscle.

Abstract

A largely forgotten technique initially designed by Sihler for staining nerve tissue has not been fully explored for staining intramuscular nerve branches in skeletal muscles. Fresh, long heads of triceps from locally bred New Zealand white rabbits were used for this study. Immediately after their removal, the muscles with their motor nerve branches from the radial nerve were fixed in 10% unneutralized formalin, followed by maceration and depigmentation in 3% aqueous potassium hydroxide, decalcification in Sihler's solution I, micro-dissection, staining in Sihler's solution II, destaining in Sihler's solution I, neutralization in 0.05% lithium carbonate, and clearance in increasing concentrations of glycerin. A clear three-dimensional orientation of the distribution of the intramuscular nerve branches within the muscle belly was visualized. It was found in all specimens that the long head of triceps in the rabbit was constantly innervated by three main intramuscular nerve branches and each of them supplied different amounts of muscle fibers with some variation. The Sihler's neural staining technique can be applied to the study of the distribution of intramuscular nerve branches in limb skeletal muscles. Extension of the technique may be utilised in the identification of neuromuscular compartments in skeletal muscles. Such information may be usefully applied in free muscle transfer of segments of skeletal muscle.