Posterior Perspective of the Infraspinatus Under the Skin

Description

Positioned on the posterior scapula, the infraspinatus occupies the infraspinous fossa inferior to the scapular spine, with its superior border closely paralleling that bony ridge as it courses laterally toward the humeral head. Medially, the muscle belly lies adjacent to the vertebral border of the scapula, while laterally it tapers into a tendon that passes deep to the deltoid toward the greater tubercle. Centerline landmarks include the spinous processes of the thoracic vertebrae, with the ribs forming a curved thoracic cage deep to the shoulder blades. Fiber direction reads from the medial scapular surface obliquely superolateral. Clear orientation. Rotator cuff teaching often bogs down at the level of “four muscles,” but the posterior view makes the infraspinatus easy to localize relative to the scapular spine, a practical landmark during physical exam and posterior shoulder approaches. This is the primary external rotator tested with resisted external rotation at the side and in abduction, and it is commonly involved in posterosuperior cuff tears that weaken external rotation and produce posterior shoulder pain. The relationship to the scapula also matters in scapular dyskinesis, where altered scapular position changes cuff loading even when the tendon itself is intact. Use this artwork in gross anatomy lab manuals, kinesiology and biomechanics lectures on glenohumeral stability, and clinical skills teaching that links palpation of the scapular spine to rotator cuff function testing. It also fits orthopedic and sports medicine content on cuff tendinopathy, tear patterns, and rehabilitation cueing for external rotation strengthening. Anatomical accuracy verified by SciePro's Medical Advisory Board.