What is the primary action of the latissimus dorsi muscle?

The primary action of the latissimus dorsi muscle is indeed adduction, extension, and internal rotation of the shoulder. This broad, flat muscle is located in the back, stemming from the lower spine and pelvis, and its fibers extend to insert into the upper arm at the humerus.

When the latissimus dorsi contracts, it brings the arm towards the body (adduction), lifts the arm backward (extension), and rotates it inward (internal rotation), which are essential movements for various activities including rowing, swimming, and overhead lifting. These functions are particularly important in sports and physical activities that involve pulling movements or reaching overhead.

Understanding the actions of the latissimus dorsi is crucial for both assessment and rehabilitation in kinesiology, as well as for enhancing athletic performance and preventing injuries.