This is the function of any body - to do the will of that person. The Body of Christ has structure, but it is a structure designed for flexibility.
Sinews are the muscles of the body, designed for movement.
Ligaments join the muscles to the skeleton, which creates the body's structure. Without structure, the body will collapse. This is not just doctrinal agreement, but agreement in purpose and vision. We are not to think more highly of ourselves nor more lowly of ourselves than we should. Do nothing out of selfish ambition or vain conceit, but in humility consider others better than yourselves.