causes of neck and shoulder muscles to harden
Sitting in a position where the head is held forward of the shoulders, such as reading or computer use, makes the upper back and shoulder muscles constantly work to hold the head up. Tension may build up due to daily stress. This causes tightness to build up in the upper shoulder and neck muscles, and can cause neck muscle strain. In the event of an unexpected sudden twisting movement, a car accident, or unaccustomed repetitive use of the neck, the neck muscles may become sprained or strained.