Anatomical Relations
As its name suggests, the coracoacromial ligament attaches from the lateral border of the coracoid process to the apex of the acromion of the scapula. Together, the inferior aspects of the acromion, coracoid process, and the coracoacromial ligament form the coracoacromial arch. This arch forms a protective roof over the head of the humerus, thus, preventing superior displacement from its glenoid cavity.
The coracoacromial ligament is bordered superiorly by the clavicle and deltoid, and inferiorly by the tendon of the supraspinatus muscle and the subacromial bursa. It is continuous with the deltoid fascia superiorly and the clavipectoral fascia medially.
Related parts of the anatomy
Structure
The coracoacromial ligament is a strong, broad, triangular band. The ligament is most commonly seen as Y- or V-shaped (42–75%), but may also be seen as undivided (26–58%) or multibanded (1–15%) (Rothenberg et al., 2017). The coracoacromial ligament is described as being fibrocartilaginous, including areas which are calcified.
Function
The coracoacromial ligament is a strengthening ligament and plays a role in stabilizing the glenohumeral (shoulder) joint. By being positioned superiorly, it prevents upward dislocation of the glenohumeral joint. It also acts as a tension band between the acromial and coracoid process of the scapula, transmitting forces exerted on the coracoid process by the short head of biceps brachii, pectoralis minor, and coracobrachialis muscles to the acromion. Additionally, forces exerted on the acromion by the deltoid and trapezius muscles are transmitted to the coracoid process, thus limiting the distortional forces applied by these muscles (Rothenberg et al., 2017).
List of clinical correlates
—Rotator cuff disease
References
Rothenberg, A., Gasbarro, G., Chlebeck, J. and Lin, A. (2017) 'The Coracoacromial Ligament: Anatomy, Function, and Clinical Significance', Orthopaedic Journal of Sports Medicine, 5(4), pp. 2325967117703398.
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Coracoacromial Ligament
The tendon of the muscle passes deep to the coracoacromial ligament to gain insertion to the greater tubercle and the superior aspect of the capsule of the shoulder joint.
