The scapula more commonly known as the shoulder blade articulates with the humerus at the glenohumeral joint. The scapula has three surfaces: the costal, lateral and posterior.
The anterior surface of the scapula faces the ribcage. This is where the subscapularis originates (one of the rotator cuff muscles). The coracoid process also originates here which lies underneath the clavicle allowing the pectoralis minor, coracobrachialis and bicep brachii to attach at this region.
The lateral surface faces the humerus bone. This is where the glenohumeral joint is situated, the main bones around this area are the glenoid fossa, supraglenoid tubercle and infraglenoid tubercle.
The posterior surface of the scapula is the site of the majority of the rotator cuff muscles. These include the Infraspinous fossa and the Supraspinous fossa.
All 3 surfaces of the scapula are important to know to locate the site of pain/ discomfort and understand what is causing the winging.