Acromioclavicular Ligament, Posterior View

Description

Posteriorly, the scapular spine tracks laterally to the acromion, where it meets the distal clavicle at the acromioclavicular (AC) joint. A dense acromioclavicular ligament spans directly between the acromial facet and the lateral clavicle, forming a superior capsular reinforcement that sits superficial to the joint line. Inferior and slightly medial to this complex, the glenohumeral articulation between the humeral head and glenoid fossa lies deeper, with the proximal humerus descending distally from the joint. Portions of the upper ribs frame the thoracic wall anterior to the scapula. This posterior perspective is the practical way to teach why an AC joint sprain behaves differently from a glenohumeral instability event. Disruption of the acromioclavicular ligament contributes to horizontal (anteroposterior) instability of the distal clavicle, while vertical displacement in higher grade separations correlates more with injury to the coracoclavicular ligaments (conoid and trapezoid), which are not prominent from a strictly posterior surface view. Small structure, big consequences. Clinically, the relationships shown here map directly onto mechanism and exam findings after a fall onto the lateral shoulder, and they help clarify what surgeons mean when they describe clavicular override and posterior displacement patterns. Sports medicine and orthopaedic teaching sessions often need a clean AC joint surface anatomy view for Rockwood classification discussions, operative planning for AC stabilization, and figure panels in journal reviews on AC reconstruction techniques. Anatomy faculty can also drop this into upper limb modules when contrasting the AC joint capsule, acromioclavicular ligament, and the deeper glenohumeral stabilizers during posterior shoulder dissection labs. Anatomical accuracy verified by SciePro's Medical Advisory Board.