Infraspinatus Under the Skin

Description

Posterolateral right shoulder anatomy is presented with the skin made translucent, leaving the scapula, clavicle, proximal humerus, and cervicothoracic vertebrae as stable landmarks. The infraspinatus occupies the infraspinous fossa inferior to the scapular spine, its fibers converging laterally toward the humeral head, deep to the posterior deltoid that caps the shoulder. Along the lateral border of the scapula, the infraspinatus lies superior to teres major and blends with teres minor near the greater tubercle, forming a continuous posterior rotator cuff sheet adjacent to the glenohumeral capsule. Orientation is clear. This view matters when you are teaching or planning around posterior cuff pathology, because the infraspinatus tendon inserts on the middle facet of the greater tubercle and directly tensions the posterior capsule during external rotation. Weakness in resisted external rotation, a positive external rotation lag sign, or selective fatty atrophy on MRI often tracks back to infraspinatus dysfunction, either from tendon tearing or suprascapular nerve entrapment at the spinoglenoid notch. For arthroscopic repair, appreciating the infraspinatus footprint relative to the deltoid and scapular spine reduces confusion between true cuff tissue and overlying posterior deltoid fibers when working in the subacromial space. Use this artwork in gross anatomy and kinesiology modules to pair scapular landmarks with rotator cuff insertions, or in sports medicine teaching on overhead athletes where posterior cuff overload and internal impingement are common discussion points. It also fits orthopedic and radiology publications explaining rotator cuff tear patterns, spinoglenoid ganglion cysts, and surgical portals for posterior shoulder arthroscopy. Anatomical accuracy verified by SciePro's Medical Advisory Board.