"A concussion is a type of traumatic brain injury. It is caused by a bump, blow or jolt to the head or by a hit to the body that causes the head and brain to move rapidly back and forth. This sudden movement can cause the brain to bounce around or twist in the skull, creating chemical changes in the brain and sometimes stretching and damaging brain cells.”1
1. Centers for Disease Control and Prevention [Internet]. Atlanta (GA): Centers for Disease Control and Prevention; [cited 2019 Feb 11]. What is a concussion?; [reviewed 2017 Jan 31; updated 2017 Jan 31; cited 2019 Feb 11]; [about 2 screens]. Available from: https://www.cdc.gov/headsup/basics/concussion_whatis.html