Shoulder Bursae Anatomy

From top left, clockwise. Subdeltoid Bursa, Infraspinatus Bursa, Coracobrachachial Bursa, Coracoclavicular Bursa, Teres Major Bursa, Subscapular Bursa, Subcutaneous Acromial Bursa and Subacromial Bursa.

What is a Bursa?

A Bursa, or the plural Bursae sometimes called Synovial Bursae, are sacks of tissue filled with fluid. This fluid is similar to that of raw egg white. Bursae provide a buffer between tissues and function as a gliding surface to reduce friction and keep the major joints of the body able to move freely and smoothly. Bursae reduce friction between tendons and bone, ligament and bone, tendons and ligaments and between muscles.

Every major synovial joint in the body as several Bursae, usually the more range of motion a joint has the more Bursae is requires. The Hip has 4, the Elbow has 2, the Ankle 3. The shoulder has approximately 6 Bursae with an additional 2 nearby.  

Bursae of the Shoulder

The 6 Bursae of the shoulder are:

1. Subdeltoid Bursa: Permits smooth movement of the rotator cuff deep into the Coracoacromial arch.

2. Subacromial Bursa: Lessens friction and ensures smooth movement of the Supraspinatus tendon deep into the Subacromial space.

3. Subcutaneous Acromial Bursa: Protection of the Acromion.

4. Subscapular Bursa: Lessens friction between the Subscapular tendon and the shoulder capsule, Coracoid process and the Scapula neck.

5. Infraspinatus Bursa: Lessens friction between the Infraspinatus tendon and the shoulder capsule.

6. Coracobrachachial Bursa: Lessens friction between the Coracobrachialis tendon and the Coracoid process of the Scapula.

Other Bursae exist around the area of the shoulder.

1. Coracoclavicular Bursa: Lessens friction between the Coracoclavicular ligament and the Clavicle.

2. Teres Major Bursa: Lessens friction between the Teres Major and Latissimus Dorsi tendons.

Injury to Bursae

Bursae injuries are most commonly caused by trauma, inflammation of a joint and overuse. In swimming athletes, the most common cause will likely be overuse due to the high repetition and unnatural movements of swimming. Overuse can lead to inflammation of a Bursa due to the high and constant friction between the Bursa and the tissues it lies between. Joint inflammation is also a high risk for swimming athletes, tissue inflammation in the shoulder can lead to both Subacromial and Internal Impingements, should the tissues in which the Bursa lies become inflamed then this can increase the risk of the bursa becoming inflamed as well. Impingements also cause a narrowing of the Subacromial space which can also because bursae can also become compressed during overhead movements.

This inflammation of a Bursa is known as Bursitis, should the injury be due to infection this is called Septic Bursitis and Aseptic Bursitis if no infection is present. Other potential injury risks to Bursae injury include