Ever wonder what happens to your brain during a concussion? 🤕 A concussion is a mild traumatic brain injury caused by a direct or indirect hit to your head or body. Your brain sits inside your skull surrounded by fluid. When your head or body takes a hit, your brain shifts or shakes around inside the skull. 🧠 The impact damages your brain cells, causing chemical and cellular changes in the brain. Learn more. | UPMC Sports Medicine