Subtendinous bursa of subscapularis muscle

The subtendinous bursa of the subscapularis muscle is a constant anatomical structure located deep to the subscapularis muscle and tendon, separating it from neighbouring bursae such as the coracobrachial, subcoracoid, and subacromial bursae.

Anatomical relations

• Roof: The subtendinous bursa of subscapularis is related anteriorly to the deep surface of the upper subscapularis tendon and adjacent muscle fibres.

• Floor: At its floor, it is related to the root of the coracoid process, neck of the scapula, and anterior glenohumeral joint capsule.

Superior Extension

In 80% of cases, the bursa extends superiorly beneath the coracoid process, forming an anterior overhang along the upper edge of the subscapularis tendon. This is a normal anatomical feature, though it may mimic adjacent bursae on imaging.

Joint Communication

Unlike other shoulder bursae, the subtendinous bursa of subscapularis normally communicates with the glenohumeral joint through an aperture between the superior and middle glenohumeral ligaments. It does not communicate with the subacromial, subcoracoid, or coracobrachial bursae.

Histology

The subtendinous bursa of subscapularis is lined primarily by areolar synovium (roof) and fibrous synovium (floor), reflecting functional adaptation to friction and pressure against the scapula and joint capsule.