Which of the following describes the actions of the teres major?

The teres major is a muscle that plays a significant role in the movement of the humerus. It is located in the posterior aspect of the shoulder, originating from the inferior angle of the scapula and inserting on the medial lip of the bicipital groove of the humerus.

The correct answer identifies the actions of the teres major as extension, medial rotation, and adduction of the humerus. This muscle functions primarily to extend the arm from a flexed position, engage in medial rotation (turning the arm inward), and assist in adducting the arm (bringing it closer to the body). These actions are crucial for various upper limb movements, particularly those involving pulling or lifting motions.

Understanding the specific movements of the teres major is essential for assessment and rehabilitation in individuals with shoulder injuries or conditions, as it contributes significantly to the overall stability and mobility of the shoulder joint.