Infraspinatus Bursa

bursa musculi infraspinati

The infraspinatus bursa is a small bursa located between the infraspinatus muscle belly and the posterior glenohumeral joint capsule, reducing friction between the deep infraspinatus and the capsular surface as the arm internally and externally rotates. It does not normally communicate with the glenohumeral joint but may do so in large rotator cuff tears allowing communication between the joint and the posterior soft tissues.

Region: Shoulder

Clinical Relevance

Clinical Notes

The infraspinatus bursa can become distended with fluid in the setting of posterior glenohumeral joint effusion communicating through a posterior capsular defect, or from direct infraspinatus tendon pathology. On MRI it appears as a fluid collection between the infraspinatus muscle and the posterior capsule. In posterior shoulder approaches for labral repair and capsulorrhaphy, the infraspinatus bursa is the tissue plane used to approach the posterior capsule. Communication of this bursa with the joint through a posterior rotator cuff tear can be identified on arthrography.

Pathology

Common Injuries & Conditions

Posterior Rotator Cuff Tear with Bursal Communication

Full-thickness posterior cuff tears allow glenohumeral joint fluid to communicate with the infraspinatus bursa and the posterior soft tissues, producing an MRI pattern of both glenohumeral effusion and posterior peritendinous fluid that localises the cuff defect to the infraspinatus or teres minor.