STRESS-STRAIN PHENOMENA IN HUMAN PERIPHERAL NERVE TRUNKS

Abstract

The strength and elasticity of large peripheral nerve trunks have been investigated with particular reference to (a) Maximum loads irrespective of size. (b) Maximum stress per unit area of nerve trunks. (c) Maximum stress per unit area of funicular tissue. (d) Elongation at the elastic limit and at mechanical failure of the nerve. (e) The distribution of the lesions as the point of mechanical failure is approached and passed. Maximum tensile strength of nerve trunks varied from 0.5 to 3.1 kg. per sq. mm., maximum tensile strength of funicular area varied from 1.7 to 6.2 kg. per sq. mm. Evidence points to the importance of the funicular tissue as opposed to the epineurim in resisting tension. The elastic limit of a peripheral nerve trunk is of the order of 20%, complete mechanical failure occurs at maximal elongations of 30%, however for some nerves it may be as low as 8%. An important factor is the rate of application of the load. The dependence of the stretched nerve trunk on the integrity of the funiculi and the rupture of the nerve fibers before fracture of the perineurium were noteworthy features. The extensive longitudinal distribution of the lesions as the elastic limit of the nerve was exceeded is confirmed.