The teres major is responsible for which of the following actions?

The teres major is primarily responsible for internal rotation of the shoulder joint. This muscle is located on the posterior side of the shoulder and plays a crucial role in movements that draw the arm closer to the body and rotate it inward. Understanding the functional anatomy of the teres major also highlights its importance in various activities, such as lifting and different forms of overhead movements, where internal rotation is essential for optimizing strength and stability.

In this context, other movements such as abduction, elevation, and flexion do not accurately describe the primary action of the teres major. For example, abduction involves moving the arm away from the body, elevation refers to raising a body part, and flexion pertains to decreasing the angle between two body parts – none of which are the principal actions of the teres major. Instead, this muscle's main function focuses specifically on internal rotation, which is vital for numerous functional movements in daily activities and sports.