The Anatomical Structure of the Infraspinatus Muscle in a Male

Description

Spanning the infraspinous fossa on the posterior surface of the scapula, the infraspinatus forms a broad, triangular muscle belly that narrows laterally into a tendon inserting on the middle facet of the greater tubercle of the humerus. Superiorly it lies inferior to the spine of the scapula and the supraspinatus, and inferiorly it approaches the lateral border where it blends with the teres minor. Laterally, its tendon passes deep to the posterior deltoid and contributes to the posterior rotator cuff, sitting posterior to the glenohumeral joint capsule. Posterior shoulder anatomy is where many rotator cuff problems hide in plain sight. Isolated infraspinatus weakness or atrophy often points to suprascapular nerve compromise at the spinoglenoid notch, classically seen with paralabral cysts or repetitive overhead activity, and it presents differently from a more proximal lesion at the suprascapular notch that also affects supraspinatus. This posterior view also clarifies why infraspinatus tears can spare forward elevation yet produce a marked loss of external rotation strength and a positive external rotation lag sign. Clear landmarks matter. For teaching, this illustration suits upper limb anatomy labs, musculoskeletal and sports medicine lectures, and rotator cuff modules in orthopedic or physical therapy curricula where students must link scapular fossae to tendon insertions and exam findings. It also fits surgical and radiology publishing contexts that discuss posterior cuff tears, arthroscopic posterior portal orientation, or suprascapular neuropathy patterns in male shoulder pain. Anatomical accuracy verified by SciePro's Medical Advisory Board.