Muscle knots in the Pectoralis Major Sternal Section are typically located in the broad, upper portion of the chest muscle, closer to the sternum and extending toward the armpit. These knots can cause pain directly in the chest muscle itself and may also refer discomfort into the front of the shoulder, down the inner arm, and to the elbow. This area often tightens up from activities like heavy lifting, push-ups, or prolonged slouched posture.