Function & Location of Shoulder Bursae

Bursae (plural for bursa) are flattened sacs of synovial fluid that function as cushions between your 1) bones and muscles (deep bursae) or 2) bones and tendons (superficial bursae) to reduce friction and allow your soft tissue to slide over bone easily during muscle use. Bursae are lined with synovial tissue that secretes fluid rich in protein and collagen. This slick fluid helps the bursa act as a lubricating buffer between areas in your body where friction (rubbing) is greatest.

Bursae of the Shoulder

In amongst your bones, muscles and tendons in the shoulder there are 8 bursae, the most of any single joint in your body. The major bursae in your shoulder include: the subscapular bursa, the subdeltoid bursa, the subacromial bursa, and the subcoracoid bursa. View more non-shoulder specific information about bursae here.

The major bursae of the shoulder are as follows:

Subscapular Bursa

The Subscapular Bursa is located between the tendon of the subscapularis muscle and the shoulder joint capsule.

Subcoracoid Bursa

The Subcoracoid Bursa sits between the coracoid process of the scapula and the shoulder joint capsule.

Subacromial Bursa

The Subacromial Bursa is situated below the acromion process and above the greater tubercle of the humerus -lessening the friction when you move your arm or raise it overhead. The subacromial bursa protects the supraspinatus tendon from rubbing against the coracoid process and acromion.

The subacromial is the bursa in the shoulder that is most commonly affected by bursitis. It acts as a cushion to allow the supraspinatus tendon to slide smoothly over the neighboring soft tissue and bone. Due to its location and relationship to the acromion and supraspinatus, the subacromial bursa tends to be most at risk of being impinged or irritated.

The most common symptom of subacromial bursitis is experiencing pain when lifting overhead. This is because the head of the humerus is compressing the swollen bursa against the glenohumeral joint and the underside of the acromion. If you have pain when lifting over head, however, it could indicate one or more soft tissue injuries in the shoulder. Subacromial bursitis is very often diagnosed alongside other rotator cuff problems or impingement syndrome.

Subdeltoid Bursa

The Subdeltoid Bursa is located between the deltoid muscle and the shoulder joint cavity. This bursa protects the deltiod muscle - cushioning it from bones in the shoulder joint capsule. The subdeltoid bursa and subacromial bursa are quite close together and are usually joined together.

Bursa Swelling

When a bursa becomes swollen, the sac itself can develop little tears and may cause tears to the surrounding soft tissue. In some cases, the inflamed bursa also becomes infected with bacteria (referred to as septic bursitis) and in such cases it is important to get to a doctor asap as they can quickly become life threatening.

If you are looking for information about bursitis in the shoulder, please take a look at our shoulder bursitis information & treatment page here.