Which muscles are primarily responsible for internal rotation of the shoulder?

The latissimus dorsi, teres major, and subscapularis are the primary muscles involved in the internal rotation of the shoulder. Each of these muscles plays a vital role in this action:

• The latissimus dorsi is a large muscle that spans the lower back and extends to the humerus. It is heavily involved in shoulder adduction and internal rotation, making it a key player in movements that bring the arm toward the body.
• The teres major, often referred to as the "little lat," assists in internal rotation, adduction, and extension of the arm at the shoulder joint.
• The subscapularis is one of the four rotator cuff muscles, lying underneath the shoulder blade. Its primary function is to internally rotate the humerus and stabilize the shoulder joint.

These muscles work together to facilitate internal rotation effectively. Understanding the actions of these specific muscles is crucial in both rehabilitation and training settings, particularly for individuals wanting to enhance shoulder function or recover from injuries.