A whiplash injury occurs after a rear-end collision in a car. The injury results through the following momentum: the body is propelled forward, and the head flips back followed by the movement of the head forwards once the body has come to a standstill. Most injuries improve within weeks or months with no long-term damage to the neck.
When the muscles at the back of the neck are tensed too much or are not functioning optimally, neck pain and tension headaches can occur. Stress and tension lead to a tightening of the muscles that can cause headaches and migraines, as can bad posture or excessive time spent sitting at a computer.