Male Infraspinatus Muscle, Posterior View

Description

Posteriorly, the infraspinatus occupies the infraspinous fossa of the scapula, spreading as a broad triangular muscle belly inferior to the scapular spine and deep to the posterior deltoid margin. Its fibers converge laterally into a tendon that passes toward the greater tubercle of the humerus, just inferior to the supraspinatus and superior to the teres minor. The medial border anchors along the scapular medial margin, while the lateral edge approaches the glenohumeral joint line. Clean geography. Functionally, this is the prime external rotator of the shoulder and a key posterior component of the rotator cuff that compresses the humeral head into the glenoid during abduction and overhead activity. A posterior perspective helps you teach why infraspinatus tendinopathy and partial thickness tears often present with pain on resisted external rotation and why atrophy can accompany suprascapular nerve entrapment at the spinoglenoid notch, a pattern commonly associated with posterior labral pathology or paralabral cysts. It also clarifies the relationship to the scapular spine, a reliable landmark when planning posterior portals in shoulder arthroscopy. Use this illustration for gross anatomy and kinesiology modules on scapulohumeral rhythm, for sports medicine or orthopedic texts discussing rotator cuff injury patterns, and for patient education materials explaining posterior shoulder pain and weakness after overhead sports. It also fits clinical teaching sets on physical examination maneuvers such as resisted external rotation and the external rotation lag sign. Anatomical accuracy verified by SciePro's Medical Advisory Board.