What is the primary action of the teres minor?

The primary action of the teres minor is to stabilize the shoulder joint, particularly by preventing upward slippage of the humerus during abduction. The teres minor is one of the rotator cuff muscles, which play a crucial role in maintaining the position of the humerus within the shallow glenoid cavity of the scapula. This stabilization is essential to allow for smooth and coordinated movement of the arm, especially when lifting it away from the body.

While other muscles are responsible for actions like internal rotation or adduction of the humerus, the teres minor primarily contributes to stabilization, allowing the glenohumeral joint to function effectively during dynamic movements. This prevention of upward slippage helps to maintain the integrity of the shoulder joint and prevents injuries during activities that require lifting or overhead motion.