When musicians complain about shoulder pain, they often direct their attention (and discomfort) at the arm bone or the back of the shoulder, or scapula region. But one of the sneaky culprits to shoulder and neck pain, as well as shoulder and arm bone misalignment, is the pectoralis minor. It's the mischievous sibling to the larger and more well known pectoralis major, which attaches at the clavicle, sternum, and arm bone and lies atop pec minor. Now the pec minor is of particular interest to musicians (and honestly most desk/computer workers) because when working well, it can help to stabilize the shoulder joint, but when it's short or inhibited, the shoulder and arm bone will slide forward, in protraction and/or internal rotation. Let's demystify those last two anatomical words first, though.
If you take a look at this man's shoulders, you can see that the one on the left sits on the table. The scapula, or shoulder blade is rooted down, whereas the right shoulder blade is elevated off the table and the front collarbone is higher on the right that the left. This would most likely be restriction of the pectorals on the right side, which not only pulls the arm bone and scapula forward (protraction), but also can internally rotate the right arm. What does that internal rotation look like? In laymen's terms, it means gorilla arms.
So now we have a working understanding of what this muscle group can do to the shoulder, at least in standing. But how did we get to have restricted pectorals in the first place? For string players, our right side bow arm tends to be internally rotated and will often slide forward. If you take a look at this image of Anne-Sophie Mutter, you can see that her right arm is moving forward from her spine and ribs. If you couple that with a lot of forceful playing, extreme pronation in the bow arm (i.e. lots of first finger and thumb pressure), and/or lots of playing at the tip of the bow that can exacerbate things. In addition, perpetual tremolos in orchestra, i.e. a Bruckner/Mahler symphony extravaganza, especially loud sustained tremolos will ask a lot of the shoulder and forearm.
So now we have a basic idea of how the pectorals might get short, abused, or overused in string players, but what about with other instrumentalists? And how might it affect your performance and playing and how can you help restore its natural length and function? More on that next time.