The most obvious structure is the subscapularis tendon (Figure 5.18), the secondary landmark of shoulder arthroscopy. The superior border is quite clearly intra-articular, lying in a synovial recess between the superior glenohumeral and middle glenohumeral ligaments. This synovial recess is a constant anatomical feature2 - the opening to what used to be termed the subscapularis bursa. This is a misnomer for a bursa is, by definition, a synovial sac containing synovial fluid which does not connect with a joint. The subscapularis recess is actually a constant synovial outpouching, as is the suprapatellar pouch in the knee, and the term 'subscapulars bursa' should be dropped in favour of 'subscapulars recess' or pouch. The entrance to the subscapulars recess is called the foramen of Weitbrecht. In the lateral decubitus position used for shoulder arthroscopy, the subscapularis recess is the lowermost part of the joint, and is favoured by gravity as a hiding place for loose bodies.
Figure 5.18 Subscapularis (s) appearing from behind the middle glenohumeral ligament (m).