If you are having any numbness or tingling of your arm, the pectoralis minor (named minor because there is also a pectoralis major) is always guilty unless proven otherwise.
Look at how the pectoralis muscle lies directly over the neurovascular bundle (the nerve, vein, and artery) and you can imagine how tightness of this muscle can complicate any upper extremity nerve issue including carpal tunnel syndrome. Make sure you have your therapist check and treat the pectoralis minor, it could be a “major” problem. Let me know if you have any questions~thanks
Ed Deboo, PT
Physical Therapy Bellingham, WA