Mechanical stretching is known to cause morphologic and functional changes in peripheral nerve. The points at which these changes occur, however, are not clearly defined and reported data are conflicting. The studies presented in this paper provide a basic understanding of the biomechanical properties, stretch-injury patterns, and changes of conduction properties of peripheral nerves due to stretching. Our studies showed that peripheral nerves exhibited nonlinear stress-strain characteristics when placed under tension. Initially, under tension, the nerve had a low modulus that increased gradually with increasing strain until reaching a maximal value. When the nerve failed under tension, the perineurium inside the nerve ruptured, but the exterior of the nerve remained intact. Our results also show that a peripheral nerve in situ was under significant strain, but minimal in situ stress (less than 0.05 MPa). The in situ strain might vary with limb position, but did not appear to exceed the limit beyond which...

https://www.tandfonline.com/doi/pdf/10.3109/17453679209154780

Strain, stress and stretch of peripheral nerve Rabbit experiments in vitro and in vivo

This chapter provides the basic principles that underlie the field of ergonomics and their application to some of the current issues of importance in the workplace. Sections 2 to 4 deal with the physiology of muscles; biomechanics; cellular responses to tissue, nerve, and joint injuries as they relate to cumulative trauma disorders; and common types of overuse syndromes. The remaining sections deal with applications of the principles to workplace ergonomic issues and proposed ergonomic regulations.



The word “ergonomics” is made up of two Greek words, “ergo” meaning work and “nomas” meaning laws. The field of ergonomics is highly interdisciplinary. It applies principles from engineering, physiology, medicine, and psychology to the understanding of the interaction of humans with their workplace. The interaction of humans with their workplace may consist of identifying the relationship between job physical risk factors and physiological responses. For example, a specific ergonomic problem of paramount importance in the occupational health and safety is the issue of work-related musculoskeletal disorders (WMD). Some of these issues are discussed further in this chapter. The specific areas of application relevant for the field of ergonomics are defined and briefly explained.



Activities that involve repetitive stress have effects that are extremely complicated. Adding internal or external forces to the body can, as described, alter bone, joints, ligaments, tendons, nerves, and muscles. Belief that a repetitive motion will result in an isolated nerve injury without affecting surrounding joints, ligaments, muscles, or tendons is likely to inhibit appropriate care and control of exposed individuals. Additional research is needed to further characterize changes that occur, and current approaches to recognizing, managing and preventing repetitive injuries must address all tissues in the involved area.


Keywords:

Principles;
Ergonomics;
Muscle;
Skeletal system;
Anthropometry;
Biomechanics;
Physiological effects;
Stress strain;
Tissue injury;
Bone;
Joints;
Ligament;
Tendon;
Nerve;
Upper extremity overuse;
Carpal tunnel;
Low back pain;
Low back loads;
Regulations;
California standards;
ANSI Z-365;
Job analysis

Occupational Ergonomics: Principles and Applications

An in vivo study of peripheral nerves in continuity: biomechanical and physiological responses to elongation.

Peripheral nerve reconnection: mechanical, thermal, and ionic conditions that promote the return of function.

We believe that the randomness of sprout regrowth is the cause of most poor experimental and clinical functional results after nerve repair. We have elaborated a technique of repair, called "nerve reconnection," aiming to minimize randomness of regrowth. This technique enhances the precision of repair by minimizing physical and chemical damage to the stumps and by ensuring stress-free stump abutment. In this study, the reconnection technique was compared to the conventional microsuture method. First, both techniques were tested as the primary method of repair. A method of behavioral evaluation, the sciatic functional index, was used to assess the results. The reconnection groups consistently showed satisfactory functional results, even after two successive procedures. In contrast, only one-third of the animals in the suture groups reached satisfactory functional levels. In the second part of the study, animals with unsatisfactory results after primary suture were reoperated in an attempt to improve the poor results of initial surgery. The secondary procedures used were either the reconnection technique or conventional microsuture. All secondary procedures failed to improve poor preexisting functional conditions. These findings stress the importance of the original "blueprint" of the nerve and the necessity of maintaining this unique pattern during initial repair.

Experimental nerve reconnection: importance of initial repair.

Tension introduced into peripheral nerves during their surgical repair may reduce the success of this procedure.Two mechanical factors are important; the tension required to effect a repair, and th...

/pdf/tension-and-creep-phenomena-in-peripheral-nerve-4d9s2rwn3q.pdf

R. A. Dickson

Papers

Tension and creep phenomena in peripheral nerve