Teres MinorEdit
The teres minor is a small but important muscle of the shoulder, tucked into the posterior aspect of the shoulder girdle. It is one of the four muscles commonly grouped as the rotator cuff, along with the infraspinatus, supraspinatus, and subscapularis. Although modest in size, the teres minor plays a key role in externally rotating the arm and in stabilizing the head of the humerus within the glenoid during movement, particularly in the late cocking and deceleration phases of throwing and overhead activities.
The muscle’s contribution to shoulder function becomes especially evident in athletes and older adults who rely on controlled external rotation for performance or daily tasks. Because the teres minor works in concert with the other rotator cuff muscles, injury or weakness can disrupt shoulder mechanics and lead to pain or instability. Understanding its anatomy helps in diagnosing and treating injuries that involve the posterior aspect of the rotator cuff and the surrounding neurovascular structures.
Anatomy
Origin: the lateral border of the scapula, superior to the teres major. This positioning places the teres minor on the posterior aspect of the shoulder, deep to the deltoid muscle. The anatomical relationship with the lateral border of the scapula is essential for its function as a stabilizer of the glenohumeral joint. scapula
Insertion: the greater tubercle of the humerus, specifically at the inferior facet. This insertion allows the teres minor to act on the humeral head during external rotation. humerus and greater tubercle of the humerus
Innervation: the axillary nerve (C5–C6). Injury to this nerve can impair external rotation and shoulder abduction, reflecting the close neural control of this muscle. axillary nerve
Blood supply: primarily the circumflex scapular artery, with contributions from the posterior circumflex humeral artery, providing perfusion to this relatively small muscle in the posterior shoulder. circumflex scapular artery posterior circumflex humeral artery
Relations and boundaries: the teres minor lies just above the teres major and forms part of the posterior shoulder envelope. It is situated near the quadrilateral space, through which the axillary nerve and posterior circumflex humeral vessels pass. These spatial relationships are clinically relevant when evaluating nerve injuries or posterior shoulder disorders. quadrilateral space
Function in the rotator cuff system: the teres minor primarily produces external rotation of the arm and assists in adduction. It also contributes to the stabilization of the humeral head in the glenoid during arm elevation and rotation, working in concert with the infraspinatus to ensure smooth, controlled shoulder motion. external rotation glenohumeral joint
Function and biomechanics
Externally rotating the arm is the teres minor’s chief action, but it does not act alone. It coordinates with the infraspinatus to resist internal rotation and to keep the humeral head centered in the socket during arm movements. The synergy among the posterior rotator cuff muscles, including the teres minor, is essential for shoulder stability during throwing, pushing, and overhead tasks. Dysfunction in the teres minor—whether from strain, tendinopathy, or nerve injury—can manifest as weakness in external rotation and an unstable or painful shoulder. infraspinatus rotator cuff
Clinical significance
Common pathologies: isolated teres minor pathology is less common than injuries to the supraspinatus or infraspinatus, but tears, tendinopathy, or tendon elongation can occur, especially in overhead athletes or after shoulder trauma. Such conditions may present with weakness in external rotation and posterior shoulder pain. teres minor tear (where discussed in the literature) and rotator cuff tear contexts are relevant for differential diagnosis. external rotation
Diagnosis: clinical evaluation often includes tests that probe external rotation strength and the posterior rotator cuff’s integrity. A specific maneuver known as the Hornblower sign (testing teres minor involvement) can help distinguish teres minor pathology from other posterior cuff issues; imaging with MRI or ultrasound is frequently used to confirm the diagnosis. Hornblower sign magnetic resonance imaging ultrasound
Treatment: management ranges from conservative approaches—physical therapy focused on strengthening external rotation and scapular stabilization, activity modification, and analgesia—to surgical repair in selected cases with persistent weakness or rupture. PT aims to restore function and prevent compensatory movement patterns, while surgery is reserved for cases where nonoperative care fails or where the tendon is significantly torn. physical therapy rotator cuff tear
Prognosis: many individuals recover function with targeted rehabilitation, though outcomes depend on the extent of injury, patient age, and adherence to a structured conditioning program. In athletes aiming to return to high-demand overhead activity, gradual progression back to sport is essential. rehabilitation
Debates and policy context (treatment approaches)
Within medical practice, there is ongoing discussion about the best balance between nonoperative and operative care for rotator cuff-related injuries, including those affecting the teres minor. Proponents of conservative management emphasize evidence-based PT, gradual loading, and cost-conscious care that minimizes surgical risks and recovery times for many patients. Critics argue that delaying surgery in appropriate cases may prolong disability or lead to suboptimal functional restoration. In practice, decision-making often depends on patient goals, age, activity level, and preferences, as well as the availability of high-quality rehabilitation services. Imaging strategies and access to care—driven by insurance coverage, cost considerations, and health system design—also shape treatment pathways. The emphasis, in this view, is on delivering effective, efficient care that maximizes function while avoiding unnecessary procedures. physical therapy rotator cuff tear magnetic resonance imaging