acromial

Acromial refers to the acromion, the bony prominence on the scapula that extends laterally over the shoulder joint. The acromion forms part of the shoulder’s bony architecture and serves as a key attachment site for muscles and ligaments, contributing to the protection and movement of the glenohumeral joint.

Anatomy and relationships: The acromion is the lateral extension of the scapular spine. It articulates with the clavicle at the acromioclavicular joint, and together with the coracoid process and coracoacromial ligament helps create the coracoacromial arch, which acts as a roof over the humeral head. The inferior surface of the acromion lies near the tendons of the rotator cuff, particularly the supraspinatus, and is adjacent to the subacromial bursa. The deltoid muscle attaches along the superior surface and anterior edge, while the trapezius contributes fibers to the acromial region.

Morphology: The acromion can vary in shape. Classification commonly cited in clinical settings (Bigliani) distinguishes flat (Type I), curved (Type II), and hooked (Type III) acromions. These variations influence the size of the subacromial space and the likelihood of impingement of rotator cuff tendons during shoulder elevation.

Clinical significance: Variations or overuse can contribute to subacromial impingement syndrome, rotator cuff tendinopathy, and subacromial bursitis. Acromial spurs or a hooked acromion may narrow the subacromial space and irritate the supraspinatus tendon. Imaging assessments, such as radiographs or MRI, frequently evaluate acromial morphology and its relationship to shoulder pathology.

Etymology: The term derives from the Greek akros (top, summit) and omion (shoulder), reflecting its position at the shoulder’s upper outer aspect.