抄録
For mobility training of the shoulder joint in cases presenting restricted movement, it is important to understand the pattern of movement and the angles of all the joints forming the shoulder complex, including changes in the sternoclavicular, acromioclavicular, scapulohumeral, and scapulothoracic joints. In this research, differences in the starting and finishing distance of muscles surrounding the shoulder girdle during shoulder joint flexion and abduction were surveyed using a skeletal model. X-ray images were obtained at intervals of 30° between 0° and 180° during shoulder joint flexion and abduction of the right upper arms of seven healthy male subjects. At each angle, the shoulder blade rotation angle, the degree of slant of the collar bone, and the location of the scapular spine medial extremity were measured. These results were recreated on a skeletal model, and the distances between the muscles surrounding the shoulder joint (trapezius muscle superior fiber, mid fiber and inferior fiber, levator scapulae, serratus anterior upper fiber, serratus anterior lower fiber, and rhomboid minor and major muscles) before and after the joint flexion and abduction were measured. The characteristics of two-dimensional analysis of flexion (bone index coordinates movement analysis) comprise the separation of the scapular spine medial extremity from the spine and the movement in a caudal direction. The characteristics of two-dimensional analysis of abduction comprise approach of the scapular spine medial extremity to the spine and movement in a caudal direction. The trapezius muscle superior fiber located on the inner side of the shoulder blade, levator scapulae, trapezius muscle inferior fiber, and rhomboid minor and major muscles exhibited a complex pattern of extension and contraction corresponding to changes in the angle, unlike in flexion. We consider that, in a clinical situation, during shoulder joint movement range training, the muscle group on the medial edge of the scapula can easily become a limiting factor in joint movement range control. Moreover, in subduction, where the muscle group cannot automatically respond to changes in the angle by extension and contraction, treatment is needed on the assumption that it is a ROM control factor.
