Neuromechanical activity of the wrist muscles during stabilization tasks

Abstract

Wrist joint stability is vital to hand function and thus overall upper limb function. The overarching goal of the study is to understand the neuromuscular control and mechanical properties of the wrist muscles for wrist stabilization. Aim 1 focuses on development of an analysis method for ultrasound elastography images toward estimating individual muscle force changes in a wrist muscle. The application of multiple forces and torques at the hand and the activity of several forearm muscles to maintain stability necessitated the development of a new method of capturing and analyzing individual muscle activity. Aim 2 focuses on neural oscillations and amplitudes of muscle activity during co-contraction (i.e. simultaneous contraction for joint stability) of a wrist flexor and extensor for wrist flexion-extension stabilization and when extra afferent input is applied to the muscles. Aim 3 addresses modulation of the amplitudes of motor output via recurrent inhibition during co-activation (i.e. simultaneous activation for movement, joint stability, etc.) of a wrist flexor and extensor muscle working as synergists or antagonists for wrist stabilization. The contributions of this dissertation include new insights into the spinal and cortical control of wrist stabilization and an analysis method for capturing the activity and mechanical properties of the wrist muscles during complex wrist stabilization.