a concussion is most often caused by a sudden direct blow or bump to the head.
The brain is made of soft tissue. It’s cushioned by spinal fluid and encased in the protective shell of the skull. When you sustain a concussion, the impact can jolt your brain. Sometimes, it literally causes it to move around in your head. Traumatic brain injuries can cause bruising, damage to the blood vessels, and injury to the nerves.
The result? Your brain doesn’t function normally. If you’ve suffered a concussion, vision may be disturbed, you may lose equilibrium, or you may fall unconscious. In short, the brain is confused. That’s why Bugs Bunny often saw stars.