The latissimus dorsi muscle is a broad, flat muscle that occupies the majority of the lower posterior thorax. The muscle's primary function is of the upper extremity but is also considered to be a respiratory accessory muscle. Due to this muscle's broad attachment on the spinous processes, ongoing research is looking at what, if any, role the muscle plays in trunk movement. Currently, the evidence is mixed on how much influence this muscle has on spine extension, lateral flexion, or rotation. Even though the muscle has a broad attachment on the trunk and strong actions on the humerus, use of this muscle for surgical transposition appears to have limited effect on or restriction of normal function.