Differential movement of the median nerve and biceps brachii at the elbow in human cadavers

Abstract

Background: It is important to establish if mechanical testing for physical problems in the human is specific or non-specific for structures - e.g. muscle and nerve. The median nerve at the wrist can be moved in preference to its adjacent flexor digitorum longus muscle, but it is necessary to know if this specificity extends to the elbow. We therefore measured mechanical behaviour of the median nerve at the elbow compared to its adjacent muscle - biceps brachii.

Methods: This cross-sectional study on nine fresh frozen cadaver upper limbs used differential variable reluctance transducers and Vernier callipers to measure strain and excursion in the median nerve and biceps brachii during cervical contralateral lateral flexion in glenohumeral abduction: 0°, 30°, 60° and 90°.

Findings: Proximal excursion and strain with contralateral lateral flexion occurred in the median nerve primarily at 60° and 90° abduction (p < 0.05), but no changes occurred in the muscle (p > 0.05).

Interpretation: This study provides evidence of emphasising load to peripheral nerve over biceps at the elbow during cervical contralateral lateral flexion.

Keywords: Biceps brachii; Biomechanics; Median nerve.