Latissimus Dorsi

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Other Names Back (Middle, Outer) Lats Heads Latissimus Dorsi Movement Shoulder Adduction Extension Internal Rotation Transverse Extension Scapula (Assists) Depression Downward Rotation Adduction Attachments Origin Ilium Posterior Crest Sacrum (Posterior) Vertebral Column (Lateral Surface) Lumbar Vetebrae (L1-5) Thoracic Vetebrae (T7-12) Ribs (Posterior) Lower 3 or 4 ribs Insertion Humerus (Proximal Anterior/Medial) Intertubercular Groove (Medial Side) Related Muscles Teres Major

Comments The latissimus dorsi is a stronger shoulder adductor when the shoulder is somewhat externally rotated. It is a stronger shoulder extensor when the shoulder is neither interally or externally rotated. The latissimus dorsi does not extend the shoulder beyond anatomical position (shoulder hyperextension). In strict transverse extension, the latissimus dorsi is weak. Incidentally, the posterior deltoid is strongly involved in both shoulder hyperextension and transverse extension. The biarticulate latissimus dorsi enters passive insufficiency through the completion of shoulder flexion and abduction when the scapula is more rotated upward, elevated and abducted. The biarticulate latissimus dorsi enters active insufficiency through the completion of shoulder adduction when the scapula is more rotated downward and depressed or through the completion of shoulder extension when the shoulder girdle is more protracted and depressed.