Latissimus Dorsi

The latissimus dorsi is actually a muscle of the shoulder. However, it’s most often listed in the group of back muscles because it’s most commonly trained on the same days as the trapezius and rhomboids. The name latissimus dorsi identifies that this muscle is the largest muscle on your back, where latissimus directly translates to “broadest” and dorsi in reference to the dorsum or back side of your body (the top side, if we existed horizontally like dogs and cats). For bodybuilders, this muscle creates the hallmark V-taper from the waist to the shoulders.

Anatomy

The latissimus dorsi is a large muscle that attaches to many parts of the body. Its proximal attachments come from the lower portion of the thoracic spine; from the lumbar spine and sacrum by way of a large network of connective tissue in the lower back called the thoracolumbar fascia; and from the top of the pelvis on the back side.

Additionally, there are common variants which include attachments from the bottom 3 or 4 ribs and/or from the bottom portion of the shoulder blade. These broad attachments accumulate to one point on the inside of the upper arm (the humerus bone).

Movements

Despite having a broad attachment across many movable joints, the latissimus dorsi is most effective on the shoulder and is likely minimally effective on the spine. Ultimately, the purpose of this muscle is to pull the arm back down to a neutral position at the side of your body—specifically downwards and backwards.

The primary actions of this muscle include extension and adduction of the shoulder (embedded below). Additional actions include horizontal abduction and internal rotation of the shoulder.

The outer and lower fibers (those that attach on the pelvis and through the thoracolumbar fascia) of the muscle will be more active in shoulder extension while the upper fibers (those that attach from the thoracic spine) will be more active in adduction and horizontal abduction.

Although attaching on various portions of the pelvis and spine, research analysis is not consistent on whether or not the latissimus dorsi has notable influence over trunk (spine) movements such as extension, lateral flexion, and rotation.

Training the latissimus dorsi

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