Transverse Sliding of the Median Nerve Beneath the Flexor Retinaculum

Abstract
Transverse sliding of the median nerve beneath the flexor retinaculum during active-resistant flexion of the fingers was sonographically demonstrated. Although it is a physiological phenomenon, it may cause mechanical nerve deformation in addition to longitudinal sliding when the nerve is subject to compression against the flexor retinaculum by tensed overlying flexor tendons.