Medical Conditions - Muscle Stiffness

When you find it hard to move a muscle, and it feels tight, usually at rest, it is called muscle stiffness. The common causes of muscle stiffness include muscle sprain, muscle strain, insect bite, infection, anesthesia, and extreme heat or cold injury. If your neck feels stiff and you have a fever, consult a doctor immediately as it can be signs of infection of the brain or spinal cord.