Full Latissimus Dorsi Muscle Description
[Continued from above] . . . From its many widespread origins, it runs obliquely, superiorly and laterally through the back and armpits to insert on the posterior side of the humerus of the upper arm. As the latissimus dorsi approaches its insertion point, the many muscular fibers from its many origins merge to a point, giving the muscle a triangular shape.
The latissimus dorsi has several different functions, all of which involve movements of the arm. The primary function of the lat is the adduction of the arm, which is often used when performing a pull-up or chin-up or when pulling a heavy object down from a shelf above one’s head. Another function of the lat is extension of the arm, as in swinging the arm toward the back. This motion is used when swinging the arms while walking as well as during rowing exercises. Finally, the latissimus dorsi medially rotates the arm, moving the front of the arm towards the body’s midline. When performed with a bent elbow, medial rotation of the arm brings the hand towards the chest, like when folding the arms or touching the elbow on the opposite arm.
Prepared by Tim Taylor, Anatomy and Physiology Instructor