main outcome measures:mechanical characters of elongation and mechanical characters of viscoelasticity of superior trunk of brachial plexus nerve.
主要观察指标:臂丛神经上干的拉伸力学性质和黏弹性力学性质。
superior trunk of brachial plexus nerve was performed stress relaxation test and creeping test, and data and curve of stress relaxation test and creeping test were obtained.