The job of the trapezius is to support your head. When you injure your trapezius by pulling it, its going to have a harder time doing its job. Because of this, you might find that you have a hard time moving your head, neck and shoulders like you normally do. Aside from being the workhorse that keeps your head up, your trapezius is also connected to your arms. When your trapezius gets injured, one or both or your arms might become weak, as if there is nothing supporting it (or them). When the muscle fibers in the trapezius get stretched too far, or get torn, the muscle fibers also contract at the same time and become tight. When this happens, it can create a of block of sorts that doesn't allow enough blood to get to the area. This lack of blood can cause your muscles to spasm (it will feel like your muscle is twitching under your skin) or stiffness (which will feel like your muscles have turned to cement). As mentioned above, when the muscle fibers in the trapezius constrict, they let less blood into the area, which also means the area gets less oxygen. Oxygen helps break up lactic acid, so when there is not enough oxygen, the lactic acid builds up and creates pain. The pain can be described as sharp pain, a stinging sensation, or feeling like your muscle has been tied into knots. On top of the muscle spasms and pain caused by insufficient blood flow, not having enough blood in the area also causes a strange tingling sensation that you will most likely feel in your arms. This happens because the muscle fibers in the area are constricted.
انتبه إلى أي صعوبة تعانيها عند تحريك رأسك أو كتفيك. ارصد أي نقص في قوة أحد ذراعيك أو كلاهما. لاحظ أي تشنجات بالعضلات أو تصلب تشعر به. راقِب الألم في رقبتك وكتفيك. انتبه إلى أي إحساس وخز تشعر به في ذراعيك.