Epimuscular myofascial force transmission between nerve and myotendinous unit: A shear-wave elastography study.

Introduction: Epimuscular myofascial force transmission can occur bidirectionally between muscles and nerves through a connecting neurovascular tract. The purpose of this study was to determine whether a neurodynamic stress test produces stiffness changes in the adjacent myotendinous complex. The authors also assessed which anatomical variables had an impact on elasticity changes provoked by the maneuver.

Methods: A convenience sample of healthy adults (n = 39) recruited from a university population who met the inclusion criteria participated voluntarily in this study. Using Shear-Wave elastography, stiffness data were obtained for the ulnar nerve, flexor carpi ulnaris tendon and muscle before and after a neural tensioning maneuver.

Results: Following an ulnar nerve stretch, statistically significant differences were obtained in neural stiffness increase in nerve (p < 0.001), tendon (p < 0.001) and muscle (p = 0.046), with a moderate (d = 0.538), small (d = 0.485) and small (d = 0.224) effect sizes, respectively. The changes obtained were greater in those individuals with a smaller anatomical distance between nerve and tendon.

Conclusions: Alterations in peripheral neural tissue tension involves elasticity changes in adjacent musculoskeletal tissue mediated by the neurovascular tract. Collateral force transmission was determined by the individual anatomical differences of each subject. Future research should assess whether the observed increase in myotendinous stiffness due exclusively to the passive transmission of force through the connective bridges between the two tissues studied or if there is a "neuroprotective" muscle contraction following neural stress.