Frozen Shoulder Anatomy
To better understand adhesive capsulitis, it helps to understand the anatomy of the shoulder joint.
The shoulder joint allows motion between two major bones: the humerus and the scapula. The shoulder joint is a ball and socket joint. A depression of the scapula, known as the glenoid, provides the socket for the head of the humerus. Ligaments and muscles act to stabilize the scapular-humeral joint during range of motion and weight bearing.
The clavicle, or collar bone, connects to the scapula at the acromion, which is a bony projection off the scapula. The acromioclavicular ligaments normally surround and secure this joint.
There are four main ligaments supporting the A-C joint. One or more can be sprained (torn) during this injury. The ligaments include:
- Acromioclavicular ligament
- Coracoclavicular ligament
- Deltoid ligament
- Trapezius ligament
- Berghs BM, Sole-Molins X, Bunker TD. Arthroscopic release of adhesive capsulitis. J Shoulder Elbow Surg. 2004 Mar-Apr;13(2):180-5. 
- Buchbinder R, Hoving JL, Green S, Hall S, Forbes A, Nash P. Short course prednisolone for adhesive capsulitis (frozen shoulder or stiff painful shoulder): a randomised, double blind, placebo controlled trial. Ann Rheum Dis. 2004 Nov;63(11):1460-9. 
- Callinan N, McPherson S, Cleaveland S, Voss DG, Rainville D, Tokar N. Effectiveness of hydroplasty and therapeutic exercise for treatment of frozen shoulder. J Hand Ther. 2003 Jul-Sep;16(3):219-24. 
- Cutts S, Clarke D. The patient with frozen shoulder. Practitioner. 2002 Nov;246(1640):730, 734-6, 738-9. 
- Fitzpatrick MJ, Powell SE, Tibone JE, Warren RF. The anatomy, pathology, and definitive treatment of rotator interval lesions: current concepts. Arthroscopy. 2003 Dec;19 Suppl 1:70-9. 
- Green S, Buchbinder R, Hetrick S. Physiotherapy interventions for shoulder pain. Cochrane Database Syst Rev. 2003;(2):CD004258. 
- Tallia AF, Cardone DA. Diagnostic and therapeutic injection of the shoulder region. Am Fam Physician. 2003 Mar 15;67(6):1271-8.