The Latissimus Dorsi Muscle (also referred to in short as the Lats) is one of the largest surface muscle located on the back on either side of the back bone. It is a broad muscle that sweeps diagonally upwards across the back. The Latissimus Dorsi Muscle’s origin attachment point is the lowers spinal vertebrae, the lower ribs and lumber vertebrae and its insertion point of attachment is on the front side top of the Humerus, specifically the bicipital groove, which is achieved by its tendons wrapping around the underside of the humerus.
Recognized for it’s large flat V shape it is a very powerful muscle that is chiefly responsible for the the movement of the shoulders even though it is located on the back of the torso. When flexed the Latissimus Dorsi Muscle achieves movement of the arm in three different ways;
1 Extension: The shoulders are opened which results in the movement of the arm in a backwards direction.
2 Adduction: The shoulder and arm is brought closer to the mid-line of the body.
3. Medial Rotation: The arm is rotated inwardly.
With the shoulder in a fixed position, the Latissimus Dorsi is also responsible for lifting the mid section of the torso in an upwards direction. It is the main muscle used when we participate in the chin up/pull up exercise.
The Latissimus Dorsi also assists with breathing with the forced expiration as well as deep inspiration of breathe from the lungs.