The so-called synovial sac is a sac with synovium, which plays a buffering role between tendons, tendons and bones, or skin and bones. The synovial sac around the shoulder joint is:

(1) acromion descending capsule: located below acromion and deltoid muscle and above rotator cuff, it is the most important synovial sac of shoulder. Inflammation here is the most common bursitis. (2) Supracacromial capsule: located between acromion and skin. (3) Trapezius muscle sac: located near the scapular crest of trapezius muscle. (4) Descending capsule of scapula: located between the anterior upper part of scapula and three ribs. (5) Descending capsule of serratus anterior: located between the lower angle of scapula and the chest wall. (6) Superior coracoid bursa: the point where pectoralis minor muscle stops. (7) Two lateral sliding capsules in the intertrochanteric groove of humerus: located near the tendon stop points on both sides of the biceps tendon groove, such as pectoralis major, latissimus dorsi, teres major, etc. (8) Subscapular synovial bursa: It is located below the subscapular tendon, which is the protruding part of the synovium of the glenohumeral joint and does not communicate with the acromion descending bursa. The above synovitis is often caused by chronic stimulation or injury such as friction and impact, and the synovial congestion, edema and exudation increase, which makes the synovium swell and tension increase, resulting in severe pain, and may even cause adhesion of surrounding tissues, adhesion in synovium, fibrous atresia or calcium deposition. worship