A Technique for Studying the Kinematics of Human Joints: Part II: The Humeroscapular Joint

Abstract

The humeroscapular joint is used as an example to illustrate some aspects of an analytical technique for studying the kinematics of human joints. Coordinates of attachment points for muscles and ligaments on the humerus and scapula of a human skeleton were measured on an automated coordinate measuring machine. Coordinates of points on the contact areas between the glenoid cavity and the humeral head were measured to determine and ensure the sphericity of the joint. Muscle and ligament lengths were also measured on a cadaver of similar dimensions to the skeleton. The data were then used to determine the range of motion of the humeroscapular joint by considering the intersections of spheres mapped onto a plane. It is shown that the glenohumeral ligament limits flexion while the coracohumeral ligament and supraspinatus muscle limit abduction. It is also shown that the coracoacromial ligament does not limit the motion of the humerus before the scapula gets involved in the motion of the shoulder complex.