What Causes Muscle Spasms in the Back, Neck, Stomach, Shoulder? A muscle spasm is the forceful and involuntary contraction of a muscle, usually in the upper or lower extremities. In May causes neck pain and Back Pain Overuse, strenuous activity, or incorrect use, such as repetitive twisting or heavy lifting, Trauma, injury, or fractures. Vitamin D deficiency and insufficiency can cause neck and back pain and muscle spasms. Follow More About This:https://bigpharmausa.com/what-causes-muscle-spasm/