Infraspinatus Muscle, Posterior View

Description

Centered on the posterior scapula, the infraspinatus occupies the infraspinous fossa inferior to the scapular spine, its fibers converging laterally toward the humeral head. Superiorly and medially, trapezius forms the superficial contour of the upper back, while the posterior deltoid caps the shoulder laterally and partially overlies the rotator cuff. The infraspinatus tendon tracks toward its insertion on the middle facet of the greater tubercle of the humerus, just posterior to the supraspinatus footprint. Fiber direction is clear. Posterior visualization of infraspinatus matters because external rotation strength and posterior cuff integrity are frequently tested in clinic, and atrophy here can be the first surface clue to suprascapular nerve compromise. Compression at the spinoglenoid notch, classically associated with paralabral cysts from SLAP-type labral tears, preferentially denervates infraspinatus while sparing supraspinatus, a pattern that helps localize the lesion. This view also supports teaching the relationship between the rotator cuff and the deltoid, a practical distinction when interpreting posterior shoulder MRI for infraspinatus tendinopathy, partial-thickness articular-sided tears, or fatty infiltration in chronic cuff disease. Use this artwork for shoulder anatomy labs, musculoskeletal ultrasound teaching (correlating probe placement over the posterior greater tubercle with the infraspinatus tendon), and surgical education around posterior shoulder approaches where deltoid and posterior cuff intervals guide safe dissection. It also suits figure labeling in sports medicine texts discussing external rotation deficits, posterior shoulder pain, and return-to-throwing protocols. Anatomical accuracy verified by SciePro's Medical Advisory Board.