@bradleyblair83: Internal and external rotation of the shoulder occur primarily at the glenohumeral joint, where the head of the humerus articulates with the glenoid fossa of the scapula. This joint is a ball-and-socket joint, allowing a wide range of motion, but it relies heavily on muscular and soft tissue support for stability. During internal rotation, the humeral head rotates medially around its long axis. In this movement, the anterior surface of the humerus turns towards the body’s midline. This action is facilitated primarily by the subscapularis, which is the only rotator cuff muscle located on the anterior surface of the scapula. The pectoralis major, latissimus dorsi, teres major, and the anterior fibres of the deltoid also contribute to this motion. As the humeral head rotates internally, there is a coordinated posterior glide of the head within the glenoid fossa, and if the arm is abducted, there’s also a slight anterior translation to maintain joint congruency. Scapular stabilisers like the serratus anterior and trapezius help to maintain the scapula in a stable position against the thoracic wall to allow effective movement of the humerus. In external rotation, the humerus rotates laterally so the anterior surface turns away from the midline. This movement is primarily driven by the infraspinatus and teres minor, which are two of the posterior rotator cuff muscles. The posterior deltoid also plays a role, particularly when the arm is abducted. During this motion, the humeral head must glide anteriorly within the glenoid fossa while rotating posteriorly around its axis. External rotation, especially when the arm is elevated, is essential for clearing the greater tuberosity of the humerus from the acromion, particularly during overhead activities. #osteopathy #osteopath #manualtherapy #shoulderpain

Bradley Blair

Open In TikTok:

Region: NZ

Friday 18 July 2025 08:49:20 GMT