PROBING MULTI-SCALE MECHANICS OF PERIPHERAL NERVE COLLAGEN AND MYELIN BY X-RAY DIFFRACTION

Review written by Dr Carlo Wood info

BACKGROUND & OBJECTIVE

A better understanding of the multi-scale link between macroscopic loading and micro-scale effects of the biomechanics of the connective tissue and myelin is required in neurodynamics. Myelin has mostly been studied in isolation instead of in a multi-scale mechanical environment of the whole nerve. The transverse compression induced by tensile loading has been observed in vitro, but its effect on the microstructural elements within the core of the nerve are unknown. These authors investigated the multi-scale mechanical properties of the microstructure of nerve collagen and myelin by X-ray diffraction during macroscopic tensile loading.

The major difference between the musculoskeletal and nervous system biomechanics is that the nerves needs to conduct impulses during movement, and movement comes with potential consequences for the nerve.

METHODS

Sciatic nerves were harvested from rats and stored in a method to not alter the mechanical properties of collagenous tissues, retraction properties of nerve or undergo any Wallerian degeneration. After thawing and mounting, ink marks were made for measurement of whole tissue strain. To highlight the undulating epineurial collagen structure, nerves were imaged. The 6 nerves were loaded to failure. X-ray diffractometry and X-ray diffraction pattern analysis were carried out. Stress-strain data was calculated only for axial tissue and collagen deformation. Strain in the whole tissue was measured axially and transversely from images taken by a HD camera.

RESULTS

There are a number of findings from this study:

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