Muscle knots in the Iliocostalis Thoracis are typically located in the mid-back, along the ribcage between the lower and upper ribs. These muscle knots often refer pain to the mid-back, ribs, and side of the torso, and can even mimic conditions like rib dysfunction, intercostal neuralgia, or thoracic spine issues. People often describe the pain as a dull ache or tightness that worsens with deep breathing, twisting, or sitting for long periods—especially with poor posture.