Concussion Information from U.S. Dept. of Health & Human Services

A concussion is a type of brain injury that changes the way the brain normally works. It is caused by a bump, blow, or jolt to the head. It can also occur from a fall or blow to the body that causes the head and brain to move rapidly back and forth. Even what seems to be a mild bump to the head can be serious. To help you recognize a concussion, see below.
CDC Concussion Fact Sheet.pdf, 53.21 KB; (Last Modified on October 21, 2011)