06/10/2025
💪 Role of Infraspinatus, Teres Minor & Subscapularis in Shoulder Stability
🤝 Synergistic Activation with Deltoid
During overhead activities, the infraspinatus, teres minor, and subscapularis work in synergy with the deltoid to maintain dynamic shoulder stability.
🧭 Directional Force Balance
As shown in posterior view (Fig. for right shoulder), the resultant force vector (R) for infraspinatus and teres minor includes:
🔁 Rotatory Component (RR)
⬇️ Translatory Component (RT)
⛓️ Counteracts Deltoid's Superior Pull
The downward translatory force (RT) opposes the upward pull of the deltoid, preventing excessive superior translation of the humeral head.
🧲 Medial Compression into Glenoid
The rotatory component (RR) pushes the humeral head medially into the glenoid fossa, maintaining joint congruency and stability throughout motion.
(Source in the com-ments!)