The lats are the biggest muscle covering your back. They insert on the front and inside of your humerus(arm bone), just below your shoulder. They originate on your iliac crest (pelvis) , your lower ribs, and thoracic vertebra 7-12, and also attach on your shoulder blade.
In addition to the knee pain report I last posted, I would like to share one technique that could help alleviate you knee pain. It is a self mobilization while moving your knee. A rotated tibia and fibula are fairly common and could be the cause of stress on different structures in your knee. Try this out. Please comment if you have any questions.