The nerve and vascular supply of the latissimus dorsi come from a discrete neurovascular pedicle in the axilla. This allows the bulk of the muscle and overlying skin to be mobilized as a substitute for the pectoralis major muscle following radical mastectomy for cancer of the breast. The latissimus dorsi muscle is a landmark for the lumbar (Petit's) triangle. It forms the posterior boundary, while the inferior boundary is the iliac crest, and the anterior boundary is the external abdominal oblique. Lumbar triangle hernias are seen in all age groups and are more common in males, arising more frequently on the left side.