Muscle knots in your Latissimus Dorsi (the “Lats”) are generally located along the side of your torso and lower back, running along the back edge of your armpit and the lower rib cage area. These muscle knots can refer pain to the front of the shoulder, down the back of the arm, and even into the ring and little fingers, sometimes mimicking nerve pain. People often feel a dull ache or tightness that worsens when reaching overhead, lifting heavy objects, or pulling motions like swimming or rowing.