Acromion bursitis

The acromion bursa is also known as the deltoid bursa. It is one of the largest bursa of the whole body, located below the acromion, coracoid ligament, and deep deltoid fascia. Above the rotator cuff and humerus tuberosity (Figure 1). When the shoulder joint is abducted and internally rotated, this bursa slides with the humerus tuberosus below the acromion and cannot be touched. The acromion sac has many protrusions, the most obvious extending to the lower acromion. In addition, the sac attached to the supraspinalis muscle has a small base and a large free margin, which is very advantageous for shoulder movement. Therefore, the acromion bursa is very important for the movement of the shoulder joint, and is called the second shoulder joint.