Muscle knots in the Subclavius are located just beneath the collarbone, where the muscle connects the clavicle to the first rib. These trigger points can refer pain to the front of the shoulder, upper arm, and forearm. They may even extend into the thumb, index, and middle fingers, often mimicking thoracic outlet syndrome or nerve compression. You may feel a tight, band-like ache across the chest or collarbone, along with numbness or tingling in the arm and hand, especially when carrying heavy bags or working with arms outstretched.