The latissimus dorsi, or lats, are the broad V-shaped muscles that link your arms to your spinal column. They support and stabilize your spine while also strengthening your shoulders and back. The term "lat pull-down" refers to a common exercise for the latissimus dorsi. You can also call these muscles "backers" because they help bend your arm downward toward your body, allowing you to reach things off of shelves and into pockets. The lat is so important in maintaining good posture that people who lack this muscle often suffer from poor back health. They may experience pain when moving their torso forward or backward because the underlying structure is not strong enough to support them. A person who lacks the latissimus dorsi may also have difficulty raising their head high because the muscles that normally help them do so are not working properly. People usually think of the chest as the main group of muscles that lifts its owner's head and arms into the air. But it is actually the lat that pulls them upward. The triceps are the muscles in the upper part of the arm that bends the elbow and helps lift objects over one's head. However, the latissimus dorsi is the larger muscle that controls the movement of the triceps. So, instead of using the triceps, people with weak lat muscles need to use their chest to lift heavy objects.