Diagnostic Musculoskeletal Ultrasound in the Evaluation of the Teres Minor

Rotator cuff injuries are one of the more common injuries that occur in the shoulder. Four muscles and tendons make up the rotator cuff. These include the supraspinatus, infraspinatus, subscapularis, and the teres minor. The teres minor is the smallest of the rotator cuff muscles. It originates from the middle third of the lateral border of the scapula, just below the insertion of the teres major. It inserts onto the inferior facet of the greater tubercle of the humerus. The teres minor is innervated by the axillary nerve, and its muscular action is that of external rotation, and it can be a weak abductor of the shoulder. It is part of a larger force couple between the rotator cuff group and the deltoid, which stabilizes the humeral head during humeral elevation. Although the teres minor can be torn in massive rotator cuff tears, it is also commonly overused during repetitive activities requiring overhead lifting or external rotation. An accurate diagnosis of teres minor overuse, partial tears, or ruptures is essential for appropriate treatment planning and optimizing patient outcomes. Diagnostic musculoskeletal ultrasound (MSKUS) offers a portable, real-time, and cost-effective alternative that is gaining traction in rehabilitation and sports medicine settings. MSKUS has emerged as a valuable, non-invasive imaging modality for evaluating rotator cuff injuries, including tendinopathy, muscle strains (partial tears), and ruptures. MSKUS is excellent at detecting changes in tendon and muscle composition and continuity. This manuscript will review the utility of MSKUS in evaluating teres minor tendon and muscle injuries, including anatomy, common injury mechanisms, sonographic techniques, and clinical implications for those in the rehabilitation profession. By integrating MSKUS into clinical practice, providers can improve diagnostic accuracy, enhance diagnostic confidence, monitor healing progression, and guide rehabilitation strategies to achieve optimal patient outcomes for those with teres minor injuries.